You'd be surprised.
Depending on where you go you can be as a little as a day's walk from a village/farm/town. However that is all dependant on how fast your able to move, what the weather conditions are like, and if you can actually navigate.
I'm always surprised by the number of people i've seen wandering about looking for signposts now and then when they've wandered off the marked trail with no map/ compass or GPS. Look up a few stories from mountain rescue teams, you'll see plenty with the person concerned having got lost for 2/3 odd days before someone phoned the police to report them missing, no phone, no map, only took some snacks and a waterproof.
In the highlands the weather can change pretty fast, going from cold to snow and fog in about an hour or less. It isn't a bad idea to just stop, get a shelter & fire sorted and wait it out. Navigating around the top of a munro in a whiteout is an experience to say the least, especially when you end up at a near sheer drop.
All true but there are very few realistic scenarios in the UK or indeed anywhere else that are likely to be improved by having something like a Dartmoor Knife about your person or in the boot of your car rather than a map, FAK, SAK, torch and Bic lighter or other bits and bobs up to the same (nearly 1kg) weight and bulk as a survival knife.
If serious tree surgery is likely a Laplander (or cheap Aldi/Lidl alternative), cheap machete or axe are far more useful (and easier to explain to anyone looking in the boot of your car or pack) than something that looks like a Rambo knife.
Personal confession here - as soon as I got my diving ticket many years ago like everyone else I went out and bought a huge stainless steel knife with a picture of a shark on the handle (about the same size as a Dartmoor Knife) - essential for anticipated underwater battles with sharks, killer octopus, SMERSH agents and lots of other Walty fantasies.
It didn’t take too long to realise that the greatest underwater peril was getting tangled in abandoned fishing lines and nets that get wrapped around wrecks and having a small razor sharp knife, surgical scissors and net/seat belt cutter dotted around your rig made far more sense than having Excalibur strapped to your ankle.