I usually go to most of the pre season games and have never had a problem getting in and I always pay on the gate.
Hey relax, the spirit of these games is very friendly, so just turn up and pay on the turnstile. I may make enquiries about the Wimbledon game as it will be a far bigger deal.
depends whether they decide to charge as much as stevenage did last year! X-D Why there isn't a St.Albans City friendly this year I don't know.