There is sometimes a pressure-reducer inside the cold inlet valve where the flexy pipe is attached - have a look and take it out if there is one.
If no-go on that, have a look at the m/c spec. and see what minimum water pressure is required. Compare to the minimum spec. your water company quotes - probably 1.0 Bar. You can probably get them to check it. But not sure they can easily do anything about it.
Installing an expensive pump on the mains inlet side seems an unnecessary luxury given that all UK-supplied washing machines ought to work at the minmum pressure spec. quoted by the water companies.
Try running the machine in the evening - pressure varies according to the time of day, lowest likely to be in the morning.