I think you will be ok there gorter but not 100% sure. There is a pdf document produced by UK CAA which has lots of FAQs on it and your question is addressed but I am unable to copy and paste for some reason.
In essence, it states that ain April your JAR licence will automatically become an EASA licence and all ratings will run to their JAR expiry date. At or before the calendar expiry date of your JAR (EASA) licence you must apply for a full EASA licence. All ratings that are valid on your JAR licence will be transferred. Those that are not valid will not officially be transferred but UK CAA will make a separate note on your licence of any ratings you have held that are no longer valid. Subsequent renewal/revalidation would be in accordance with EASA Part FCL requirements.
Hope that helps.
Bananas
