Been spamming this thread somewhat today, but started reading it last week and haven’t had time to reply until now…
First ever clubbing experience, which seems wholly improbable now, was actually a rock night on Leicester Square. A mate from school and me must have been all of 14 at the time, and decided to catch the train up to London and attempt to get into a nightclub (we had had some limited success getting served in pubs by this point). Not knowing anything about nightclubs at this point, we of course headed straight to the bright lights of Leicester Square where the bouncers literally laughed in our faces when we tried to get into The Hippodrome. A guy handing out flyers clocked us and said that he could get us into a place 100 metres down the way. This turned out to be what is now the casino on Leicester Square right next to Empire Leicester Square. Sure enough we were whisked straight past security and found ourselves in an actual real life club, which even better was playing actual rock music. The name of the night was The Hellfire Club and the only song I can definitely remember them playing was Get In Line by The Atom Seed. Had zero money for drinks and had to catch the last train home around midnight, but still a very exciting night. No one at school on Monday believed that we had managed to get into an actual London nightclub. However, the seed had been germinated…
…and a lad in my year’s older brother told us that he knew of a rock club that let underagers in. So the following weekend we all piled into said older brother’s Talbot Sunbeam and drove to the wilds of South London (Bellingham) to visit a place called The Saxon Tavern. Older brother didn’t even come in with us - just said that he’d sleep in his car and take us home when we were done. He did however warn us to look out for local biker gang The Road Rats. Assuming this was winding up younger kids nonsense we confidently paid our £3 and got in. Sure enough, it was a proper biker bar full of middle aged massive bearded guys. Saw my first even instance of real drug taking that night. The music was terrible (literally the only things they played that we would dance to were The Cult, AC/DC and Run Like Hell by Pink Floyd) but nonetheless we started going fairly regularly, even though the locals and staff alike blatantly hated us. The same guy would always drive us up and then just wait for us in the car outside, which now seems incredibly sad. With the benefit of hindsight, I think he just wanted someone/anyone to hang around with and a bunch of kids two years his junior was the best he could do 
Finally someone in my social circle made friends with someone far cooler than us, and they told us about The Venue in New Cross (coincidentally I now live just down the road from this), which a) was on the train line up from Sevenoaks and b) apparently did not care what age you were on the door (I saw one of my younger sister’s mates in there one time when she must have literally been 12). This was my first experience of indie clubbing proper and remains a watershed moment in my life. The place was on three levels, and would have bands in the big room around 10ish and then different flavours of indie/rock on the three dancefloors throughout the rest of the night. The band playing on my first visit were The Sandkings, who were absolutely dreadful - late era baggy nonsense, who actually managed some minor success and also featured JasMan who would later go on to brief high profile success as Babylon Zoo. The real flashbulb moment of that first visit was when we were just getting ready to leave, the opening chords of Smells Like Teen Spirit sounded and there was literal stampede for the dancefloor. I had never heard Nirvana by this point, but this looked like something I should get involved in and sure enough it was like a bomb going off in my head. I remember moshing like a madman and gripping my mate by the arms shouting ‘What Is This?’. I think that moment is where my love of alternative music was properly cemented - I spent the rest of the weekend with MTV on hovering near the video recorder waiting to capture this elusive song so that I could play it again (I had no other way of finding it at the time - ah, technology). Started going to The Venue every single weekend after that - the combo of live band and indie disco was a potent one. Saw loads of bands on the up (and down) at that place - Senser, The Verve, Sheep On Drugs, Zodiac Mindwarp, Jacob’s Mouse, Carter USM, Sultans Of Ping, New Model Army, Suede, PJ Harvey, Billy Bragg). Heard so much music there for the first time. In fact, as much as I have always loved gigs (as in, they are probably my single favourite leisure activity and have been for my entire adult life), what indie clubs offered back then was a way to hear new music that was otherwise largely ignored by the mainstream. Before Radio 1 fully got on the britpop bandwagon and XFM finally got its licence (and then almost instantly turned to crap), hearing alternative music was fucking difficult. There were a couple of shows on MTV, the alternative chart on The Chart Show and that was about it. Heard stuff like Rage Against The Machine, Cypress Hill, Smashing Pumpkins, loads of others for the first time on the dancefloor of The Venue.
On the subject of which, much like the OP, enjoyed After School Club very much in the early 00s. Abiding memory of this place was hearing Fischerspooner’s Emerge for the first time, which on a packed dancefloor through a big soundsystem just sounded immense. Remember them also playing the full length of DJ Shadow’s Blood On The Motorway which was also great.
Also used to hit up Collide-a-scope which was fun. Spent one NYE here and there was a fire alarm just before midnight which saw us all turfed out into the freezing cold minus coats which, along with the 10 or so beers I’d drunk by this point, absolutely did for me and I spent the rest of the evening sitting in a corner trying to sober up.
Was also a big fan of Kill All Hippies at the warehouses out the back of Kings Cross before they gentrified the whole place, particularly as when it started it was free entry. Again, the bands plus DJ combo really worked for this place. Caught Ladytron, Whitey, Hot Chip, Campag Velocet (does yer man from these still post on here?), Six By Seven, loads of others here.
Don’t get clubbing much these days, but did get to visit Scandals in Portsmouth last year, which is the thinly veiled’s old university haunt. She confirmed, much to my suspicions, that it hadn’t changed much since the late 90s. Still had the same DJ in fact. Great fun, although the ceiling is a bit low - I would literally bang my head if I pulled off some of my more advanced dance moves.
Man, that’s a long post 
And features a lot of underage drinking - the 90s were definitely a different time.
Good luck with your 40th night @CdiGrassi - sounds like it will be a blast 
