FIrst of all, I would say do not approach any agencies where they ask you for money without meeting you for an interview. You do not need to audition and you do not need to pay for an interview. You don't need to get scantily-clad either!! Your best bet is to get hold of a copy of "Contacts", that you can buy (for less than a tenner) from Spotlight, at 7 Leicester Place, London W1 (they have a website, not sure of the address, but they are very good with advice). I can't recommend any agencies north of London I'm afraid though - good luck!!!