Scotland has Scandinavian style "Right to Roam" and wild camping is very popular - you can camp pretty much anywhere you want as long as you follow some sensible rules (some extremely popular areas near to Glasgow have local by-laws controlling camping - but that's a very small part of the country).

Here's something to give you a taste of what is possible:

https://www.youtube.com/watch?v=opAWJnD0Jro&t=40s

https://www.visitscotland.com/accommodation/caravan-camping/...

Also if you don't fancy staying in a tent there is a network of bothies where you can stay for free (at least during normal times):

https://www.mountainbothies.org.uk/