I've just had mine revalidated by experience (was due to lapse on 21st Sept this year) and it sounds like you should too!
If you've flown as P1 or P1/s for more than 12 hours in the last 12 months of validity of the licence AND at least 6 of those hours have been P1 AND you have flown at least 1 hour with an instructor, then you can be revalidated for a further 24 months by any CAA Examiner. It's just a case of filling in a basic form, getting the examiner to sign it. He'll revalidate your class rating in your licence and off you go for another 24 months.
Well - that's what I understand anyway!
Cheers