Your boiler is struggling because there is trapped air inside the heating system, which is making the pump sound noisy and preventing water from circulating properly.

DIY fix possible

Turn off your boiler and let the radiators cool down completely.Use a radiator key to bleed every radiator in your home, starting from the lowest level and working your way up to the highest, until only water comes out.Check your boiler's pressure gauge and top it up to the manufacturer's recommended level (usually between 1 and 1.5 bar) using the filling loop.