As above, going solo is absolutely fine. Any decent site will do an induction for rentals, and airsofters tend to be a friendly bunch - you'll always find folk keen to help out if you say "It's my first day."
Ask someone about their gun and see if you can get them to shut up.
There are a few who take skirmishes too seriously but I like to think most airsofters are a friendly bunch. Asking about their gun(s) is a good ice breaker in making new friends and acquaintances. Be warned that some will happily talk for England.