https://www.anglianpumping.com/product/water-boosting-pumps/cbm240e-230v-7230670
I put it before the pre filters so before the tank float valve shut off.
When the tank is full and the float valve shuts the water flow off and the pump senses that there's no flow and turns itself off/on automatically.
The best bit is my psi has gone from 30 to 70 psi!
Still need to tidy the pipes up but at least it works.