Thanks Whopity and DD for your comments.
I will try the New Horizons Academy, however by the sounds of Whopity's comments this won't be possible. This being said I have already sat ground exams at a different flying school to that where I was trained and recommended (albeit also in the UK) so I'm not sure if this makes a difference. Not quite sure if you mean should a referral be made by my flying school this will be possible...?
I have been in touch with AOPA and they have informed me that I can sit the ground papers at any ATO within Europe..