Camping other than at formal campsites is termed 'wild camping' in the UK. The Snowdonia National Park website states:
Can I camp anywhere in the National Park or do I need permission?
A. Although camping should be confined to authorised sites, the Snowdonia National Park Authority accepts that wild camping on un-enclosed fell land, remote from the roads, is generally accepted if undertaken responsibly by small numbers of people.
If you wish to camp on un-enclosed fell land you must:
> seek the permission of the landowner
> be out of sight of any road or dwelling
> not leave any litter
> not light any fires
As most of the land suitable for wild camping is not owned by the Snowdonia National Park Authority, we are not therefore in a position to directly permit wild camping. We advice everyone who wishes to go wild camping to have landowners’ consent.
http://www.eryri-npa.gov.uk/visiting/faqs http://www.lakedistrict.gov.uk/visiting/wheretostay/wildcamping [i]🅱