Your UK licence is non-expiring. You will be renewing the SEP(Land) class rating with the training and skill test that has been specified.
You may be issued with a new licence (possibly with a new number if you have an old 5 digit PPL), but it is effectively a renewal of your old licence with a new class rating.
Class rating requirements & privileges on UK licences are now virtually identical to JAR ones except that it is restricted to UK registered aircraft. You may however fly other JAR registered aircraft with day/VMC only privileges. So no real advantage in converting to a JAR licence.
The FRTOL is non-expiring and you need do nothing (a brush up with the latest CAP413 - available online - may be a good idea).