You don't make it clear if its the licence that lapsed or if its the SEP rating that lapsed. All JAA licences became EASA licences in Sept 2012 so you only need to take action as you approach the 5 year expiry point. You can complete SRG1104 and obtain an EASA licence document which will be a lifetime licence. You do not need a valid Class rating to do this. You can then revalidate or renew the SEP rating when you get back to UK.
If its the SEP rating that has lapsed, then you can renew it when you get back to the UK, you now have to go to a RF or ATO to obtain a Course Completion Certificate before completing a proficiency check.
You will need an assessment of Level 6 English in order to obtain the new licence this may already have been completed.