Quite a few of my clients live in this area but they always prefer an outcall to a Central London hotel. However, I think if you pick well, you should be ok. Will send you details of a hotel I once had to do an outcall to.

My only advice to you is be very careful in your selection of apartment.   Many overseas executives and foreign diplomats live in these areas and therefore they have "covert security".  Areas like St. John's Wood and Hampstead have private security firms that patrol on foot and by vehicles and they do hesitate to question you if you seem suspicious so bear that in mind for your clients.  An old friend lived on Avenue Road and I can tell you that the security that patrol that road are probably ex-military (scary azz mofos)!!!