I don't know what pre-thermostatic means but we have one of these installed:
Hand held shattaf / bidet spray in chrome with hose, wall bracket and stop cock. Converts any toilet into a hygienic bidet. Ideal for Muslims requiring an Islamic bidet. Ideal for washing. Easy to install. Manual stop cock included. Wall bracket included. Shower hose included. Pipe connection...
www.taps4less.ie
It's plumbed to the cold tap only as far as I'm aware but it's fine to use! I guess the water in the hose & pipe is within the heated part of the building envelope so is room temperature. If you let it run for a few minutes it might get cold alright but that doesn't happen.