Combi boiler: close heating flow and return safely?

[diy_dude]

I have a glow worm UltraCom 30cx combi boiler. Is it safe to close the heating flow and return valves and continue to use the hot water?

I have some repairs to radiators and valves I need to do before it gets cold. It may take me an evening or 3 to get it done and the Mrs cannot cope without hot water.

I would turn the heating control on the boiler off to prevent the 3 way valve opening. The expansion tank and bypass cable are both built into the boiler?

Is this a good or daft idea? If daft, is there any other way I can keep the heating on while I replace several leaking radiator valves and a rusted radiator?

 

[diy_dude]

I decided to go for it.
I turned off the heating flow and return at the boiler and drained the heating loop. The boiler pressure gauge stayed the same and the hot water worked for a couple of days like this. I have not refilled the system and added new inhibitor and we are back to normal but now without the leaking valves and radiator.