Hi TW.
It would appear that your PPL became invalid in 2004 due to the expiry of your SEP(Land) rating. This also coincides with the time you completed your fixed wing training.
As your rating expiry has not exceeded five years,the requirement will now be to complete an LPC/SPA (Licence Proficiency Check/Single Pilot Aeroplanes) on a suitable Aeroplane eg.Warrior/172 even a Firefly, with an Examiner.
This will take the form of a simple General Handling exercise. - Stalling, Steep Turns, Practice Forced Landing, Ccts. etc. May be a good idea to have a bit of a practice with an f/w instructor first.
Also appears you could be at CD (?) so your nearest Aero Club could be at Perranporth where they'll doubtless have an Examiner on call.
Oh, and check your CAA Medical validity.
Hope this helps.
Rgds,
Sleeve Wing.