No room to fit circulation pump, any suggestions on what to do?

[barnabyrees-jones]

I am replacing an air source heat pump. The current hot water tank, valves etc are all staying so should be a fairly straight forwards procedure, however the new heat pump doesn't have an internal water pump or flow switch which both need fitting to the plumbing system. Surely the water pump needs to be fitted on the flow and return before valves etc incase the bypass valve is active and the water is circulating in the smallest loop of the water tank if say the UFH actuators are all closed and not calling for heat. I have attached a few photos to try show it a bit more clearly. The flow and return enter the water tank shed under the black flexible conduit to the left of the flow setter you can see in the photos. Any suggestions on where and how I fit both the circulation pump and flow switch with such little room would be greatly appreciated. Thanks in Advance.