Typical over holiday period we have little/no hot water. the three way motorised valve isn’t working, its stuck in the heating position. Can I remove the head and move the valve manually? We have the immersion heater but at certain times of day demand outstrips supply.Thanks.

No reason why you can’t try – it my well just have stuck due to a bit of crap circulating – give it a go.

Hit it with a hammer

Some have a small lever so you can operate it manually.

Any makers marks?

I.e. Which one is it!! But yes you should be able to pop the motor off to reveal the valve itself and be able to turn the spindly manually.

Turning the spindle is fine, but, it wont turn on the HW/CH unless the microswitch inside the valve is activated.
If you have a fully pumped system, and one or the other is working now, then no problem, move the spindle manually.
You can use the lever on the side of the motorised valve to do it manually, but if the microswitch is not working, then that will not work for you.
Screwfix and Toolstation are still open, where are you, someone who knows may be local to you.