There are 100s of different Acers and I is probably going to be very difficult to make an ID. I would however have a guess at Acer palmatum Orange Dream.
Can I just say that it's hardly surprising you want another that specimen is gorgeous!

You could google specialist nurseries or if you find one near take yourself of for a lovely visit.......before the leaves all drop

You do have a very attractive tree, I would actually contrast it with a nice green leafed Acer rather than trying to get the same variety. Acer shirasawanum 'Aureum' would be a good choice. If you really want to go down getting the same variety then taking a hardwood cutting from your current tree would be your best bet.

Hi

Thanks for all your responses. I have also had suggestions like Autumn Moon from a nursery but I'm not sure I've yet found the match.

I will try to take some cuttings next summer as I am getting lots of requests from family and neighbours who would like one of their own !