Just a quick update for anyone who's found themselves in the same boat as me (have CPL but no IR and therefore expired ATPL theory)
Have started studying ATPL's D/L again for the second time (oh the pain!) and am back with OATS as they gave me a fantastic deal for all the books etc second time round.
So far its actually not as bad as I thought, its been 5 years since I last studied the ATPL's but its coming back pretty well. My first couple of frames are taking about 1/3 of the suggested time and I'm getting through about 2 per week just studying a few hours in the evenings.
Will see how I get on in the exams again but so far its going pretty well and have to admit I'm quite enjoying it !