Radiators not heating up?

Hi
we moving into a house with severe problem, we have a baxi solo wm50/4rs boiler fitted and it does not appear to be working properly, pilot light is ok, ignites ok but then goes off , there is hot water going out of the boiler but does not appear to go into the tank in airing cupboard or radiators. Does anybody have an idea what the problem may be because i have not got a clue? can't afford to replace at the moment. thank you