I just revalidated my ME IR with a LBA , German examiner , and its very straightforward under EASA. The examiner emailed the UK CAA test notification team with SPECIFIC details included in the email , you can find this information on the CAA website or wherever your licence authority happens to be . The UK only asked for copies of his licence , examiner authority , and date of UK Examiner briefing. The next day my check flight was approved and didn't cost a euro , as my licence was endorsed by the examiner and hand written on my ratings page. The examiner has to fill in 4 copies of the examiner report , one of which has to be sent to the UK.
I would imagine for a brand new rating , you may have to complete an additional form and probably pay some monies for the new rating to be added to your licence. But once you have the rating , its really quite a simple process, with no fees .
jess