Thorn Olympic 20/35B Boiler.. is it the boiler's fault?

I have a Thorn EMI Olympic 20/35B boiler.

Two problems
1. Not all radiators get hot, i am going to buy some radiator thermometers to try and balance them

2. My boiler doesnt stay warm for the whole period that it is on. And it wont let me turn it on when i want it on constant. It comes on and off when it feels like it. Some times it fires up and some times not.

I have my thermostat set to the highest. 6 because its freezing and now it wont stay on for long periods. only for couple of hours at a time

Is there something that i can do to sort this out?

FIrst I'd check the pump, then the boiler thermostats.

Where can i find the pump and what does it look like. What would i be check for?

The heating comes on.. it wont stay on for long periods, it lets the radiators cool right down and then it wont let you fire it up again.

It also doesnt reach all of the radiators

BUMP