Central heat system? any heating engineers out at hand ? my boiler for the heating...

any heating engineers out at hand ? my boiler for the heating wont work i enjoy checked the pilot light and thats still on when i put the switch on the radaitors stay cold and after abut 5 mins it starts bang anyone any idea what it could be and does it nouns expensive to fix (its just for the heat not a combi) thanks cas
Very frozen to plug surrounded by and unplug...
Answers:    The pump have gone, I wouldnt ring anybody tonight, cost a fortune, if you call tomorrow and are lucky satisfactory to find somebody, about lb130, dont receive anyone who says no phone call out charge without finding out the hourly rate, and put together sure they bring a pump so they don't have to progress shopping.
What inhospitable surroundings more enthusiasm...?
check that the pump is working