Boiler makes clicking noise, plus other problems?

Hi,

I'm living in a shared old victorian house in Canada. The boiler makes a loud clicking noise, which reverberates throughout the house through the hot water pipes (it's loudest downstairs, faintest upstairs).

Our water pressure is also absolutely terrible - using a washing machine or turning on a tap on the groundfloor completely disables both the upstairs showers. It's strange, because the tap for the bath in one of the bathrooms has much, much better pressure than the shower.

Does this sound like anything fixable? The clicking noise from the boiler is driving me mad in my bedroom on the second floor!