New Water cylinder for hotpress ,do i need thermostat

I am thinking of getting new bigger water cylinder that is pre insulated to replace the one that is 27 yrs old. I have Electric shower in main bathroom that my kids use but they will use unsuite if GAS heating was on and cylinder hot.Pump shower in unsuite that I use all the time, In summer I put immersion on for 30 mins if heating not on has timer linked to phone. Should I get thermostat for the cylinder? Plumber said cylinder he getting does not have thermostat.
I have solar panels.

With no thermostat on the tank your boiler will heat the tank up to whatever temperature it is sending to your rads, which could be 70-80 degrees. The two issues with that are it could scald somebody if it came out of a tap/shower and it’s also unnecessary/inefficient to heat the tank to that temperature, 50-60 is more than enough.

The immersion will have its own thermostat, but you need a way to stop the boiler over-heating the tank. If the tank is factory insulated with an immersion fitted there might be connectors on that to cut-out the boiler too. Plumber will know once you tell them you want it though.