how offended do you think they'd be if I just wanted a massage without the extras - £40 for hour is a load cheaper than any of the 'spa's' and probably a load better than Chapel Spa.
Offended? Why would they be? They advertise massage, nothing else.
Surprised? Probably. They would anticipate you wanting those "extra" services that they don't advertise.
Will they offer you those "extra" services when you are alone with them in the room? Almost certainly.
Will you be able to resist their offer(s)? You'll need to be strong.
Tip. Decide before you go how much you are prepared to pay and take only that amount of money with you ... they are cute and difficult to resist ... and they know it.