The properties you are looking for used to exist but no more. Dunkeld, Keswick Lodore, Conrad Mount Juliet (ROI).
In England, I think there's nothing.
Dunkeld was the most recent after Hilton/owner let the property go into the ground, as usual! It had truly exceptional grounds of any Hilton property worldwide- over 300 acres next to the River Tay.
Only Dunblane is a bit like that, but you can't walk out the door and go on a proper walk. If you choose to stay there, make sure you get a room in the main hotel-not the annex. DBB rates have been enhanced to only two courses. Book your table on the website because it can be super busy and IME when its busy, the restaurant is not so good. The spa is quite tired and not connected to the hotel. As mentioned, you need a car.
I would never stay at Coylumbridge. It has terrible reviews on TA and is a kids resort. There's nothing relaxing about that hotel.
Craigendarroch has a very high standard of accommodation, but as its a HGV there's no Gold benefits of any kind.
I quite like Hilton Templepatrick in NI (you did say UK). They have some suites over the golf course that are quite nice and you don't need to go outside to use the pool. Just be aware its really a gold resort. A car would be best to visit.
Many of the Small Luxury Hotels have what you're looking for
http://www.slh.com and while it would cost more you will just have a nicer time. If you free yourself of brands, and given you're only Gold its a no-brainer IMO.