Hotel with hydrotherapy area/not just steam room somewhere north of Watford

[HolyShmoly]

Hi,

We're going from Newcastle to Watford in a couple of weeks and doing Harry Potter studios on the Friday morning. Ideally we'd like to travel a couple hours in a generally northern direction, then stay one night in a nice hotel with hydrotherapy pool/tepidarium, etc. I'll be 23 weeks pregnant so I don't want to chance a sauna or steam room as they might be too hot, but I'd love to lounge around a tepidarium or rooms that aren't as extreme in temperatures.
Ideally somewhere with a few local options for dinner and that isn't too expensive (unfortunately ruling out the ahmazing Rockliffe)
Any suggestions please?

Whittlebury Hall, near Towcester, may fit the bill?
''Tis not pretty, IMO, but has hydrotherapy pool and tepidarium. It is affordable and about an hour to Watford.
Fawsley Hall, near Daventry, is more attractive. If you are traveling with DC they are well catered for with a cinema etc.