My GP was great. But then, I only spoke to her after I had already got out, and each time I went to see her, I knew exactly what I wanted to ask her to do for me - whether it was to sign me off work, prescribe ADs, or refer me for counselling.
She did more than I asked her for, because she has excellent bedside manner: encouraged me to talk, gave me helpful practical advice on healthy eating and advce on activities to take my mind off things and lower anxiety.
But generally, with GPs as with anyone else, people very rarely know what the right thing to do is, and it helps if you already know what you need them to do to help you, and ask for it.
Yes, it would be great if there were guidelines for GPs to follow when they suspect/hear of DV, as there is for the police. (Are there such guidelines?) But even with guidelines, not every GP is going to have the right reaction every time.
It is very hard as a DV victim to get to the stage where you feel entitled to ask for help, but IME it is once that state of mind is achieved that the right kind of help is forthcoming, whether from a GP or from anyone else.
I guess I believe there should be a mix of official guidelines once DV is suspected/declared, and of DV victims taking charge of the requests for the kind of support they would like to receive.