Central heating problem

[JCJC]

Sounds like you need a pucker 'gas safe' chappie (used to be called corgi) most common problem is the thermocouple that sits in the pilot flame, when hot provides a voltage to the gas valve, big lump that controls the gas, if the pilot goes out the gas valve switches off the gas supply in case it comes back on, ain't lit and gasses you, also if the thermocouple fails then the the gas valve won't get a voltage - no gas, all good fitters will have one with them.