If your UK PPL was issued with the SEP(Land) included in section XII, then of course it can be signed on re validation even if it hasn't been since its issue. The CAA will have made the first entry. It will be quite clear to any examiner that you have maintained the SEP(land) in validity by inspecting your UK/EASA licence and should use those dates. The decision to be made is whether the action is a 're-validation' or a 'renewal'. The SEP (Land) rating is one rating and doesn't change it's status and privileges from licence to licence.
Hopefully it is on the UK CAA list of jobs to reinstate the ICAO compliant UK PPL to its proper full status. There is no need to have two licenses any more.