If it weren't for the adjoining 17th-century manor house (Rudding Park proper) you could be mistaken for thinking this glassy waterworks was in Ojai or Big Sur, or some other modish, wellness destination. Its rooftop spa sings in cold weather, when the thermal hydrotherapy pool, herbal bath steam room and sauna are all the more comforting. A day pass costs £98, but those who pick its "spa, sleep and dine" offer get dinner, bed and breakfast as well as one 45-minute treatment per guest for just £354 per room.

Panelled with rustic beams and surrounded by spindly, young silver birch trees, Calcot Spa's indoor pool is swoon-worthy. You'll also have access to a sauna, a steam room, an outdoors, fireside hot tub surrounded by tufts of lavender and seven treatment rooms serving up a menu of Elemis treatments and custom experiences, tailored to your personal taste. For the best value, we suggest taking a couple of days off work and booking its midweek spa break deal which includes an overnight stay, breakfast, unlimited time in the spa and £50 in treatments for each guest. It'll set you back £329 per room.

It might have been built in the style of a typical Sussex barn, but there's no mistaking this spa for a country bumpkin. Inside this timber-clad spa-house, you'll find a heated pool, a sauna, steam room and relaxation rooms primed for Mediterranean-inspired treatments. Half hour massages start from £61 and a manicure costs just £35. We're opting for its Sunday spa deal, which includes a three-course dinner, breakfast, a night in one of its antique-strewn bedrooms and a £60 treatment voucher for just £305.

This Elizabethan manor is outfitted with a strikingly modern, rusty-red spa. From the walk-through rainforest shower to the in-and-outdoor pool to the Isopod (a flotation tank where guests are suspended in a pool of saltwater) to the café, which dishes up all-natural smoothies and light bites, this spa is designed to defrazzle, inside and out. Spa access is only available to hotel guests, so you'll have to book a room in order to get the full works. Thankfully, "cosy" rooms are available from £189 per night.

This spa isn't winning any interior-design awards and it's a little light on baseline facilities - expect a heated pool, lemongrass-scented hot tub and stacks of loungers - but it's set in the basement of a grand 17th-century mansion and surrounded by sprawling grounds that are guaranteed to chill out overworked city-dwellers. Give Sunday blues the cold shoulder by taking it up on its Sunday Night Spa Break offer. It costs £399 per room and includes £35 towards dinner for each guest, breakfast the following morning, one hour of relaxation in the spa, a 40-minute treatment and full, unfettered use of their other leisure facilities such as their putting green and tennis court.

Hefty slabs of marble, planks of cacao-coloured wood and comforting greige tiles set the tone at this Champneys spa. Its facilities include a 20m heated swimming pool, a steam room, sauna, hydrotherapy pool and private relaxation beds flanked by curtains. It's low-key glam and not too expensive if you book wisely. An overnight spa break costs £368 per room (or £184 per person) and includes overnight accommodation, a healthy breakfast, two-course lunch, full access to its spa facilities and a 50-minute Champneys treatment.