Hi Stu...welcome to the Club
Looks like you've picked up a great car there....worth spending the money on by the sound of it.
Not 100% sure for BMW's but I would use a parts website (Eurocarparts or similar) and see if a DMF is listed for it.
If there is the option of both, then I think it is a case of finding out once you have the gearbox down.
Don's think there is any other way of telling by driving (unless its knackered and it will rattle on start up and shut down)
Let us know how you get on with it
Cheers, Trevor