Dave Liquorice wrote:

I am actually hoping for a single timer with fully independent
control over both systems - am I right in saying that the wiring
would be a little simpler ? I would like to be wireless everything.

Wireless adds pennies, quite a few pennies. If the pump, motorised
valves, wiring centre, programmer and room stat reciever are all in
the air cupboard they can be all hardwired. Wires are very reliable.

I have noticed that is expensive, but I will only need a wireless room
stat; if I wire everything as you have said (this is the plan) then the
tank stat does not need to be wireless.