Nigel,
Heres my opinion:
The PPL exams are basic knowledge on all the angles required to fly a light aircraft. During your course it will only take a couple of weeks to do the subjects and get them out of the way. So theres nothing stopping you doing a bit of reading just now on the PPL subjects to help shorten the gap between the PPL knowledge vs ATPLs knowledge. Books can easily be bought from ebay at a decent price.
Alot of the ATPL subjects expand from PPL level knowledge. So you may wish to start with a few PPL books and work your way up.
ATPL subjects are tough because of the amount of material you have to learn. Reading a couple of ATPL subjects now will no doubt make things easier for you during your course. You may read it and forget about it now but once you re-read it again during your course you will take it in alot better (apparently!).
You said you are attending a course next year. I am presuming this course includes all study materials and flying hours from 0 to fATPL...spending money just now on flying hours and expensive study packs is wasting resources which you may require during your course. As I mentioned before, ebay is a good place to get 2nd hand manuals at a fraction of the cost! (can anyone guess what route im taking?)
will