'Can I just park up and stay the night here?' is one of the most common questions new motorhome and campervan owners ask - and the honest answer is that it depends heavily on where in the UK you are, and the specific rules can and do change.
England and Wales
Generally, wild camping (staying overnight away from a designated site) requires the landowner's permission in England and Wales - it isn't a general legal right in the way it is in Scotland. Dartmoor has historically been a notable exception with a specific right to wild camp on certain commons, though this has been the subject of ongoing legal challenges in recent years, so it's worth checking the current position directly with the Dartmoor National Park Authority before relying on it. Many car parks, farms and 'stopover'-style schemes offer legitimate overnight stopping with the landowner's agreement - these are a far more reliable option than assuming you can simply park up anywhere.
Scotland
Scotland's 'right to roam' (formally the Scottish Outdoor Access Code) is considerably more permissive, generally allowing wild camping on most unenclosed land, done responsibly - though some specific areas (parts of Loch Lomond, for example) have introduced seasonal byelaws restricting it due to high demand and past misuse. Always check for local restrictions before assuming the general right applies everywhere.
Doing it responsibly, wherever you are
Whatever the local rules, the same principles apply everywhere: leave no trace, don't empty waste water or toilet cassettes anywhere except a proper disposal point, keep noise to a minimum, and be prepared to move on if asked. A single inconsiderate stay can affect the goodwill available to everyone who comes after.
The safest general approach
Because rules genuinely vary by specific location and do change over time, treat anything you read (including this) as a starting point, not a final answer - check current local signage, council websites, or specific national park guidance before relying on being able to stay somewhere overnight.