Dacorum Borough Council in Hertfordshire clearly think you should hold it in. They fined two men £88 each for peeing in a layby. The men objected, the council stood firm, but eventually the council relented and their fines were rescinded.
A layby is a bit public and not a sensible place to pee, but what if they were in the midst of a wood and totally invisible? Is it really a good use of council funds to track them down and penalise them?
I've often had a pee when I'm walking in the Mourne Mountains. As long as there's nobody else around, what's the harm? It's either that or have an embarrassing accident.
Peeing in a public street is a different matter. It's vulgar and selfish. Usually the culprits are men who've had far too much to drink and suddenly need to pee on the way home. They're oblivious to the mess they make and other people's reactions.
Theoretically you can be fined £40 for peeing in a public street, which counts as indecent behaviour. But how often do you hear of someone being fined?
Of course there should be more public toilets, but they can't be everywhere, and your chances of being near one when you need to pee are pretty low.
Just be careful what you do in a layby.