I usually fly from either Denham or Wycombe. Below is my personal list:
Beetle and Wedge Boathouse www.beetleandwedge.co.uk
Chewton Glen www.chewtonglen.com
Cliveden House www.clivedenhouse.co.uk
Fawsley Hall www.fawsleyhall.com
The Grove Hotel www.thegrove.co.uk
Hanbury Manor www.hanbury-manor.com
Lords of the Manor www.lordsofthemanor.com
Mallory Court www.mallory.co.uk
Priory Bay Hotel, Isle of Wight www.priorybay.co.uk
Tylney Hall www.tylneyhall.co.uk
Washbourne Court www.washbournecourt.co.uk
West Lodge Park www.bealeshotels.co.uk/westlodgepark
For up North, I'd second the Swan Hotel suggestion - very pleasant place for a heli lunch