However....
...to answer the original question.....
If you do want to convert, wtih north of 100 hours you'd need a skills test, UK Medical and I believe UK Air Law and UK RT exams. Just tried licence application without the RT for a PPL and although the licence has been issued, there was a nice little (pre-printed) card in it saying you have to do the RT exams for the issue of an RT licence.
LASORS Section C for PPL conversion facts and figures.