Beeing the UK CAA, or any CAA actually, I would clarify anyway that the 500 hrs can be accounted for and it is 500 total and not 500 P1.
Should it be more convenient for you, I did my sim at LH roughly same price includnd a crew up.
In the company you probably work for, there is a euro based CN who is a JAA TRE and periodically organizes TR endorsment sim sessions at Cargolux.
CAA will eventually answer and, in good old CAA fashion, will tell you read CAP 804 !
Be advised UK CAA only accepted the original logbook or a JAA type electronic logbook, they wouldn't accept logbook copies with company chop and a cover letter signed by the CP or the company online logbook !
They will also need copies of your license, medical, simulator JAA certification, TRE license and JAA examiner certification, FTO JAA certification and that is about it.
All this was from Lasors and JAA era, with EASA and CAP804 something might have slightly changed, have a good read.
Cheers