I have a UK CAA licence, did a sim at LH with a LH JAA examiner to have a valid type on my JAA licence and convert it to EASA, 500 hrs P1 was a requirement, should be pretty much a similar process under EASA.
You need an EASA certified sim and an EASA certified examiner.
You may get authorization to use a non JAA sim, depends on the national CAA.
Years agò I contacted the then JAA now EASA and if you have a case they will authorize but the request has to arrive from the national CAA and that is where I got stuck.
The examiner must definitely be EASA, can be from a country different from the licence issuing country but I Think under EASA an authorization and a briefing are required from the licence issuing CAA, I believe this is the case with UK CAA.
If you are going "somewhere else" I am pretty sure you can do it during your sim check and save the money.