If you're totally new:
Have a browse on YouTube (including Gamble's channel). There's LOADS of videos for beginners, about what you need to get started, which is actually very little:
Sturdy boots with ankle support.
Clothes you don't mind getting dirty (camo or dark colours).
Gloves are good.
Eye protection is your main priority, but if you're starting out renting that will be provided, though I'd still recommend getting your own as the rental stuff sometimes isn't the best and you don't know if it's already taken a few shots.
Then....
Go to a site close to you (check out the sites review section on this forum).
Rent a gun.
Play.
Do that a couple of times, see if you like the game.
Go on from there.
You'll find that at most sites the players are friendly, inclusive and helpful.
Hope this was of some help ?
Oh, and check out the new players section here, lots of good info:
https://airsoft-forums.uk/forum/11-new-players-amp-arrivals/