I just paid £240 for an initial at NATS in Swanwick. Very friendly and helpful and took not much more than hour (as the nurse does most of the routine tests one after another instead of you having to go back to a waiting room), but I guess it depends where you need to travel from as to whether the saving on the medical is worth it. They have their own medical department for ATCO medicals and have just been approved to do Class I initials, think they have been able to do renewals for a while, but I don't think it is widely publicised.