slightly tricky:
License and theory course need to be done under one JAA state, so, unless the LBA accepts the UK JAR ATPL theory credits, you will need to transfer your state of license issue to the UK, thus giving you a frozen ATPL. (Or is this what you meant and already hold??) I understand that the LBA can be flexible at times...
The IR is different, and I suppose it will be ME? this is a rating and thus can be done under any JAA jurisdiction. Lots of Germans doing it here (in PRG), then add it to their German license and in Croatia, where you can do a straight German IR at a school that is well known to German pilots.
cheers IP