my ideal 2000 boiler won't fire up !?

If the pilot light stays on, but the boiler won't light when you move the thermostat to position 6, then it is likely to be the gas valve. It is the most common fault, after the thermocouple.
In round figures the gas valve will be about £80 and the thermocouple [if you ever want one] about £10.
Plus VAT, but quote the RS number on the inside of the drop-down flap.

keidal
March 2016