I think you'll be safe using Helicopter Services at Wycombe, and i'll be very surprised if you're asked to pay up front there. Just pay as you go. My advice is to go visit them, and ask if you can do a quick test to see how you get on with the fnpt2, as they'll only accept you if they think you're capable of getting through the course. Well worth it. Ask Leon or whoever is there, if you can then be placed on the waiting list and, if you're available at short notice, ask if you can be considered for any cancellations. They seem to happen every once in a while. (ie funding reasons or lack thereof etc)
Good luck.
If you want any more details about helicopter services PM me. I did my IR with them a couple of years ago.
