I can see Wittering working however, perhaps not as successfully as some other options. Establishing a new R313 directly on top of Wittering would be tight squeeze up against the Sibson para DZ. You could push that airspace a bit further north, over Cottesmore but then you're nudging up against Buckminster Gliding Club at Saltby. On top of that, if there is the desire to continue as is normal at Scampton during practices, you'll need to man Cottesmore's ATC tower and Fire section. Further, whilst Wittering has an ACR currently manned by blue suits who could provide the radar services to RAFAT in the same way that Waddington currently does, when Programme Marshall kicks in, those blue suits and the radar will be relocated at Marham - not convinced Cottesmore (or Wittering) will be in "solid radar cover" in the same way as Scampton is to Waddington.
Yorkshire, IMHO, would appear to be the best bet.