Whats the maximum amount of timber you can fell with out a lisence?
it is all different in each state, contact your local authority, all the best
All states are different. If its your land you can clearcut the whole thing. Land is owned by someone. Check with the owner.
UK or elsewhere? In your garden or on land you own? Are the trees protected by a TPO? Give us a clue and someone may be able to help.
On someone's front lawn?
That depends on the laws in effect in the given jurisdiction. It varies widly.