These comments are based on my own experience of living on the road since June 2017.
There are few facilities in the UK for motorhomes that are not commercial camping sites.
Many petrol stations have an external water tap. Spend a few pounds and they’ll usually let you fill up. Keep a look out for water troughs and drinking fountains. Many churchyards have water taps.
It depends what type of toilet you have and if you can avoid using it. Keep in mind that most supermarkets, shopping centres and many garages have toilets for public use.
If you have a wet toilet cassette, empty it in a public toilet. If you’re near a canal sanitary station use that, buy a key from the Canal and River Trust.
Avoid using the blue variety of chemicals. If your waste ends up in a septic tank the chemicals destroy the bugs that allow the tank to break down the waste. I use bio clothes washing pods in the cassette.
Thick varieties of toilet paper can clump in the cassette. The cheaper thin brands break down quicker and reduce the likelihood. Some people don’t put the paper in the cassette preferring to burn it.
Caution: Wet/baby wipes do not break down and will cause blockages. Ask anyone who clears drains for a living.
If you use a composting toilet use cat litter, sawdust/shavings or something organic and absorbent. Do what you need to do in a composting bag throw in some litter etc. When it’s full tie it off so it doesn’t spill and put in the rubbish. It will breakdown over time and become compost.
Most of what we throw away is packaging from the supermarket. If necessary, I leave rubbish in a bin liner in a supermarket bin. Some councils put bins in lay bys. Sometimes one is fortunate enough to meet up with a “bin lorry” on its rounds or find a large commercial wheelie bin.
WHERE TO STOP?
I’ve been living on the road for almost four years stopping in car parks and lay-bys in the UK and Europe. The only “aggro” I’ve had is from self-gratifiers blowing their horn as they pass by. There have been a few occasions when a forest ranger or similar has advised that overnight parking is not permitted and please don’t do it again.
If they say that “Camping isn’t allowed” I make the point that I’ve not yet found a UK legal definition of “camping”. One chat was with a MoD copper when I spent a weekend on Salisbury Plain training area. We had a civilised chat and he produced the by-laws which say that “sleeping out” isn’t allowed.
The rules have to be complied with, but not without question and ensuring that the official is acting within his powers. There’s no need to get stroppy, most of them want a quiet life and don’t want to deal with paperwork etc.
The Spanish police offer guidance which I think works in most places.