Yes I’ve never known there to be a CAA known minimum altitude for VFR traffic (IFR has different requirements), except the 500ft (Rule 5) rule. Which specifies a minimum distance of 500ft in any direction from a person, structure, vehicle or vessel. If you find yourself in an area where none of these are present then you can fly at any altitude you require.
I find it difficult to be able to do this in the area I fly as you can’t really fly that low for long as you’ll definitely end up breaching this rule pretty quickly.
Someone correct me if I’m wrong however there is exceptions to this rule:
1. The A/C is taking off or landing.
2. The aircraft is in distress or executing a forced landing etc.
3. The A/C is receiving a Special VFR clearance (SVFR).