Update:
All fixed. it was in fact the lack of Aircon gas as expected. Total cost £102. It would have been £65 from amazon, however, i think the extra money has been worth it as i'm now in touch with a small local garage. Fixed just in time for the winter... lol.
thanks Magnet!
Hi Gareth,
Thanks again for your thoughts they're really useful and have helped to determine the best course of action. I will of course provide an update as things progress.
Thanks,
Alex