Hi SL,
Go to
CAA Website
The site is not the best. Select 'Licencing and Examinations' at left, then select 'Licencing' at left. Then find. 'Validation of Foreign Licences' which will refer you in turn to a very tedious index page for AIC's. On the index page, the one you want is 30.7 under - you guessed it - Validation of Foreign licences.
There requirements are fairly similar to Aus, I think: Air Law Exam, Medical and flight test. Most of the flight schools will know the ropes when it comes to dealing with the CAA.
Good luck!