Many trees are protected by Tree Preservation Orders (TPOs) which mean that, in general, you need the council’s consent to prune or fell them.
In addition, there are controls over many other trees in conservation areas and other designated areas.
You don't normally need permission to plant a hedge in your garden and there are no laws to say how high you can grow your hedge. But you are responsible for looking after any hedge on your property andf or making sure it is not a nuisance to anyone else. This means trimming the hedge regularly, both its top and all sides
If you are in any doubt about the status of the trees or hedgerows you plan to work on should contact your local council before you start.
Building regulations do not apply to trees and hedges but foundations can be affected by tree roots and soil moisture.