The reference is in CAP 804, section 4, Part Q Subpart 1, page 3, first row of the table. However, row 2 mentions co-pilot "according to operational requirements" so I guess you will need some sort of affidavit from your company stating that you fulfilled the role in a situation that required a copilot. Row c just mentions 1000 hours in commercial air transport since gaining an IR, so I guess you can get something out of all that
If you can self-certify you can get up to date study material for as little as $59.95 (it's briefly mentioned above). That plus Aviation exam would be enough, but there is a free flash-card type database at
http://www.rtfq.org.
The 36 months is for you to get the check ride and the IR ride in. If you don't get the IR, the exams run out after 36 months. Only if you obtain at least a CPL(A) and an IR will the 7 years kick in, so you effectively get 8 years, because the IR has to expire first. Put another way, as long as you have an IR, the exams stay valid. Mysteriously, for helicopters, they also stay valid as long as you have a type rating.