If your licence is of the 'old' UK PPL type, it is a lifetime licence and does not need to be re-issued.
If you are revalidating an SEP Class Rating included in your pilot licence, there is nothing to pay to the CAA.
If you are renewing an SEP Class Rating included in your pilot licence, which expired less than 5 years ago, there is nothing to pay to the CAA.
If you are renewing an SEP Class Rating included in your pilot licence, which expired
more than 5 years ago, the rating renewal fee is £87.
See
http://www.caa.co.uk/docs/175/Person...harges2011.pdf