It can be taken up to 3 months before your SEP expiry date.
General The UK IMC rating is designed as a 'get you out of trouble' qualification and not as a replacement for the IR The UK IMC rating may not be placed onto an EASA licence.
In a search for an approved examiner there I have found the UKFT ( com) . But my experience in the States was really good before UKFT - my last revalidation was in Florida, they required me to make kind of checkout in their plane with their instructor, charged this one hour and everything was done...
By Test: If done by test it can be done within 3 months prior to expiry of the class rating, and the class rating will be valid for 2 years from the date of expiry of the previous class rating.
Most examiners will do this for free or for a very modest fee. I have asked the guy, whether it was a typing error but not, he really want to have five hundert greens for the revalidation. "Surely anything you try to get done here will cost you more than doing it back home..
SRG19 form here: while Whopity's PPL examiner renews your SEP rating for free his Licenced engineer not charge you to renew your aircraft's ARC ! with an IR renewal costing 1000 each year, the instructor renewal at 600 over three years and all the other costs of keeping professional licences and ratings just how can you not charge and still put bread on the table. I am just organizing a SEP(land) revalidation during my stay in California next month. " Back home means Germany, and here the prices are quite different...
By Experience: In order to have a Class Rating (Single Engine Piston) revalidated you must have completed the following IN THE 12 MONTHS PRIOR TO THE EXPIRY DATE OF THE RATING: 12 hours of flight time in SEP or TMG aircraft as appropriate, to include; Class Rating Renewal A renewal is required if the class rating has expired. the date is after the "Valid until" date shown on the Class rating page.
Your SEP Rating needs to be revalidated every 2 years.
NPPL Licence Holder Revalidation of Single Engine Piston Rating All NPPLs remain valid for the lifetime of the holder.