Signed up, didn't get an email confirmation, phoned them up and they told me that I would have to be a guest of a member to gain admission.
I did a spa experience in Peterborough, little did I know it was kid swimming times...safe to say we did not stay long.
funnily enough I had a virgin voucher for one of these places, closest one to london was in chingford which is basically a gym which has a sauna you can use. They also do "spa treatments". The reviews on tripadvisor are hilarious, anyone in london thinking of doing this I would suggest not to waste your time https://www.tripadvisor.co.uk/Attraction_Review-g10283565-d12239277-Reviews-Bannatyne_Health_Club_Spa_Chingford-Chingford_Waltham_Forest_Greater_London_En.html
Avoid Peterborough one
Tamworth one is quite nice and friendly staff.