Glow worm hideaway boiler problems

Hi all, forgive me im a plumbing novice.

Got a problem with my hide away, it\\\'s not heating the radiators at all.

Couple of weeks ago the whole system started banging when the timer switched on for water in the morning, and now we have this issue.

The pilot light is fine, it seems to be an electrical problem.

The only way I can get it to kick in, is to turn the electrics off to the timer, turn the thermostat to zero, then turn it all again. Once I turn the thermostat on it fires up but only for about 5 mins, then turns off. If I press down on the thermostat then it fires up again, but only for a while. I manage to get two upstairs radiators working then it kicks out.

Water was boiling due to heating over night, so no issues with that.

Any help would be welcomed, please as basic as possible.

Update on this - if I leave the hot tap running while the electric part of the system is switched to heating and water then the boiler continues to fire up and heats the radiators, as soon as I turn the tap off then the boiler turns off. - confused

Thanks

Ozza

check the ball valve in your top up tank isnt stuck off

And your pump?