Less flow of water from hot water tap

It very much depends on your system. I suspect you may have a hot water cylinder in your airing cupboard as opposed to a combi boiler or pressurised system (which works off mains cold pressure) if it’s what’s known as a tank fed system (usually the tank is in the attic) then the pressure of the hot is always inferior to the cold main. This is due to the hot water being pushed through the system via gravity rather than pressure of the cold main.

The two options to fix this problem is to either have your plumber clean the water supply lines or replace them with new water pipes. Sediment and scale buildup inside the water by the tap mixer. If your water mixer tap is not that old, you could have your plumber flush and clean the sediment and scale from inside the tank.

Phone a plumber to check it out.