Hi
I've just been through this process, my licence having expired by just over 10 years.
You also need to look at Lasors F1.6 to renew your SEP (Land) rating.
Going through all the requirements I ended up taking the Aircraft Technical exam along with Communications (check Lasors B1.6 for FRTOL Renewal). As I also have a PPL(H) which had been valid within the last 5 years I was exempt from re-taking Air Law. There may have been some other exams that also needed retaking that I was exempted but I don't have my paperwork with me.
One other thing the CAA asked for before reissuing was licence was a confirmation of the date when I'd last flown as PIC.
Hope this helps a bit
Simon