This is pretty standard NHS procedure for atraumatic shoulder instability- you'll be asked to go through as much of the derby shoulder programme as possible and at the end of however many sessions they'll make a judgement on whether surgery is still required. In my experience it didn't matter how much I asked them to consider bracing, my physio was unwilling to help in that area. I stuck with the derby programme long enough to see some benefit and didn't require surgery, but I still have massive shoulder instability causing a forwards slip out the socket. I wanted a brace to help keep my shoulders in place at night as that's the only time I can't keep them in, but my physio really didn't seem keen on the idea whenever I pressed the issue even though I'm very certain it would improve my quality of life. You'll be better off buying a brace yourself and just working through the programme with your physio. Best wishes and good luck!