Pop down to the local flying school and speak to the CFI. He can look at your licence, ratings and logbook and should be able to tell you what you need to do. Without seeing these items you'll only get educted guesses on this forum.
You may only need to pass a licensing skill test (LST) after whatever refresher training you and he think is needed (assessment by the CAA is only required for multi-engine ratings). An LST is basically GH, emergencies and circuits. You'll need a current Class 2 Medical as well.
That's my 'educated guess' anyway.