I would recommend Simon & Caroline at at Wycombe Air Centre. I think the course is about £7000 which seems the average. The place is really friendly and if they like you and they have a vacancy then you will get a job there. If they have no spaces they are so helpful in finding you work afterwards.
The only thing I would say is to be careful of places where they promise you a job just because you do the course there - they generally are telling porkies!
Good luck!