ebay
you can try ebay for past students selling their old books, I know Oxfords were bought by several of the guys on our modular ground school and we were at another school!
Not surprising as they had colour pictures!! ours didnt, which makes it difficult when explaining EFIS.............
You can also try to get hold of the CD-roms, again, Oxfords Met disk was used by most us for revision at our ground school, in fact I used it to pass the subject from scratch.
Bristols distance learning package is supposed to be great, but I am not sure if you need the online support for it.