Fallen trees? would it be illegal to cut up fall trees for firewood (...

would it be illegal to cut up fall trees for firewood ( not on private property ) ?
Answers:    Yes, they belong to someone.

Prperty is either private, adjectives or public. Common and public are managed by councils on our behalf and you cannot give a hand your self to anything, even if its rubbish ( or fallen trees )

Private environment includes National trust, english nature, MINE !, and lately about most stop in the UK
That depends on where on earth they are. Not in a public park, obviously. Probably not in a state or national forest, any.