Owning your own home

I have and I haven't.

A few parts were a bit scaled up when I had it serviced and something had to be replaced but it's about ten years old and hadn't been serviced for at least six.

I have one, an have no idea what a woo based hard water doobry is?
The only issue I have is keeping the pressure topped up.
Was installed about 12 years ago.
No issues, and I'm in stockwell, which I believe is a hard water area..

yes and no.

mine's about 7 years old. the gas valve went recently so maybe a gas softener would be a better option...