I am not really sure about how it works in Britain but here we have a multitude of Art Clubs and Groups. I recently found out that I can (for free) take my artwork up to one of them to get really good images made of them. I do not even have to take them out of the frame as they have a professional, HUGE camera mounted that can photograph right through the glass with no glare. I have not gotten the photos back for the first set but they HAVE to be better than what I was doing with my personal camera. You should check into this and see if you have something local that can help with this.
Dawn Ash