noise from boiler

when i turn my heating on it fires up ok then after a minute or two it starts to bang and then cuts off then starts again then bangs and cuts off could this be a case of a new heating pump if so which pump is suitable to run 8 radiators ?????

Brutal person. Why be so nasty to a boiler? Turn gas off. Then put heating on. Check pump works by undoing large screw on motor end. Rotor can be seen then. Have newspaper ready for small water leak. If pump does not work buy one of those new pumps with three flow options controlled by switch. Warning pump may be smaller in length than your current one needing plumbing alteration.