How can I repair the pump Ariston Eurocombi?

My eurocombi boiler has five temperature lights lit when I start my boiler. I have no hot water nor heating. I suspect a pump failure by deduction. I have priced a pump online and it seems like it would be easy to exchange. 55 quid. I asked a plumber to fit but I get quotes of 250 to fit. I have looked at the job and it seems like its just 2 nuts to undo and a cable block to unplug. Correct me if I am wrong but this would take a fitter no more than half an hour BRINGING HIS WAGES TO 500 AN HOUR. I want to attempt this myself as I feel I am being ripped off. As I am not touching any gas parts this seems a simple job. Am I biting off more than I can chew?