Mate I wouldn't worry about the size of your todger. I always thought I was below average because of all the porn I watch. Having shagged about 40 prossies now I'm very proud of my little man! Remember for all the different cock sizes there's many different pussy sizes, some are insanely tight and will make you come in seconds, which after a few punts becomes bloody annoying so have wanks before hand if the girl is petite.
They don;t give a shit about the size of your cock, they've seen it all - it's part of their job. they like clean, polite and guys who turn up on time, if at all. there seems to be a lot of timewasters from what I've heard.
just go for it, you'll never look back after a couple of good punts. just be careful of your bank account - it's very addictive!
oh,and one more thing one of the best parts is giving the girl pleasure in my opinion, you will get more back. even if they are faking, i'm not always sure if they are to be honest! you're the one who's paying, they want you to come back. it is not dating.
have fun and i look forward to some reviews.