Definitely do it, it is very rewarding and you meet some really great people doing it, either the people you are helping or the other volunteers.
I’ve done several different things and currently helping at a cat rescue/re-homing place (cleaning up, feeding, etc). I’m doing this one, as I used to have a cat and haven’t been able to have one since due to being in rental, so thought this would be a way to be around for a couple of hours a week.
Have a proper think about what you want to do, so that you know you definitely want to. Be prepared to do it for at least 6 months too, as quite a few places want that and to be honest it’s better for the charities to have volunteers who want to be there a while rather than a lot of turnaround.
Someone further up suggested do-it and I would recommend having a look through the type of opportunities that are available so that you know what is out there, as you may not have thought about some of them before. Once you’ve found some type of opportunity you like, either apply through there or look for specific charities in your area doing that and approach them. It’s how I found the one I’m in now.
Most charities will require a DBS check before you start, but they normally pay for that. Some larger charities will provide formal training, but I’ve only experienced that in 1 place.
To give you a nice story, one of the things I did was help at a summer camp for orphaned children in Bulgaria. It was one of the most amazing experiences I ever had. Met some amazing people and the whole experience entirely changed the way I look at things.