Vanessa would be a great choice, she's not full on and should put you at ease. Be prepared for a few questions, she does like to find out about her clients. To have a more relaxing time, book in advance and request the top room. It is ensuite and has a nice large bed! Have a shower and Vanessa should appear at just the right time.
What and how you pay depends on the parlour. For 30 minutes at KSG, you pay 20 GBP to the receptionist and 30 GBP to the lady in the room. I normally leave it on the side table, she'll collect it without any fuss. With Vanessa, that will get you a massage, oral with and sex, along with kissing and reverse oral. Oh, Vanessa does not like to go on top but I've always fucked her in missionary as I like her kissing. She'll charge 10 GBP extra for oral without, at her discretion.
Hope that helps.
Cheers
nenio