Congratulations!
Basics:
Get an Orzly Tempered glass screen protector.
Purchase a protective carry case for it asap.
Give the grip a go for a while, but if you find yourself playing at home on the TV a lot, buy a Pro Controller when you can (they’re £70 though so aren’t a day one priority).
In terms of games, depends what you want.
Single player modern classics:
Breath of the Wild. Mario Odyssey. Mario Vs Rabbids. Picross.
Epic quests:
Xenoblade 2. Let’s go Pokémon. Octopath Traveller.
Games from last gen you may have missed:
DOOM. Skyrim. Dark Souls. LA Noire. Inside. Stardew Valley. Bayonetta 1&2. Captain Toad.
Platform games:
Sonic Mania. Donkey Kong Country Tropical Freeze. Rayman Legends. Shovel Knight. Guacamelee 2. Celeste. Super Meat boy.
Online with strange people:
Mario Kart 8. Rocket League. Splatoon 2. ARMS. Warframe. Fortnite.
Multiplayer in the room:
Snipperclips. Smash Bros Deluxe. Overcooked 2. Mario Party. Drawful 2. Mario Tennis.
Best indies around:
Steamworld Dig 2. Yoku’s island express. Horizon Chase Turbo. FAST RMX. Hollow Knight. Dead cells. Floor kids. Gris. Subsurface Circular. Oxenfree.
Off the top of my head…