You should still have a "brown" PPL somewhere, or a JAR SEP rating certificate if you converted to that regime. If you have a UK issued EASA ATPL that should include PPL privileges, but in any case your rating will have lapsed. Renewing the rating is quite straightforward. Training as directed by your chosen club or school, followed by an LPC. The "as or with", regarding a Class II, medical will depend on the reason, but we have an AME who's regularly at the airfield who can advise.
Send me a PM if you can get to Elstree and I'll talk you through the process, no obligation or charge, but please call first to make sure I'm about. (I'm away from the 31st til the 18th)