Pipes banging while no water is being used.

I have lived in a semi detached house for 5 years. Since I moved in, I noticed that my water pressure when I run a tap or shower, sometime goes down for a few seconds (up to max 5 seconds), then back to normal pressure. There is also a clanking banging sound often echoing through my house which sounds like water being turned on and off... but I can't pinpoint from where the noise is coming from. This noise happens whether I'm drawing any water or not. The noise still happens if my toilet hasn't been flushed, my washer and dishwasher are off... my Combi boiler is off.. and I am not drawing any water.
I have always assumed that I may share a water main with my attached neighbour next door and accepted it. But today I remembered they are away and no one has been there for over a week.
Neither me or my neighbour have garden auto watering devices.
I am a carer for my severely disabled daughter. The banging is really starting to upset her now.
Do any of you clever people have any thoughts on this?
Thanks