There's a school somwhere where you can do the FAA ground exams so I assume there's someone there qualified to teach FAA, Cant think for the life of me which airfield it is, someone on here will know or more than likely have the ticket. London way I think, High Wycombe maybe not sure
There's a guy at Kuki Helicopters who flys a 900 on the N register, might be worth a phonecall....