Just down the road from me too.
When I first got my P38, before having to change the BECM, I asked them about a fob for mine as it only came with one and that was knackered with the battery cover taped on.
I asked them if their system worked with all the RR P38 fobs and they said it was just the earlier ones, ie the ones without the passive immobiliser chip in the fob, so that was no good for mine.
My P38 decided to take the decision out of my hands anyway and the BECM lost all its settings and refused to accept any correct ones so had to replace it along with the locks and keys. The replacement BECM came with 2 good keys, one of which looked like it had never been used.