European here without education for a plumber, just barely scratched the profession for a few years.

Low water pressure occurs in bigger complexes with a pipe to small for the consumers. The water pressure in suburbans and cities comes directly from the local water station.

If you have issues with this, there are special armatures for low water pressure.

The cheapest improvement is replacing the water disperser with a current one.

Other then that, one could install a pump to improve the water pressure, but these things are expensive and have high maintainability costs due to pumping drinking water, not water in a heater pipe.

https://www.aquamaniac.de/rdm/

Gives you an adapter and an standalone tool. All banks should use the same API, apparently.

Maybe you can use some German bank. They allow one to interact with their API for free. I use GNU cash for it. Though I doubt that you can file your taxes via GNU cash and be aligned with current UK law. You would need to check it for your own.