Planning permission
Quite rightly, the authorities regulate activities and the building of structures in woodlands quite strictly (if they didn't every woodland would hold a mansion and woodland prices would shoot through the roof!), and the chances of you getting permission to build a house in your woodland are remote. Occasionally individual woodland workers (such as Ben Law) have succeeded but only after a long battle where they have had to prove that their presence on site is essential for their forestry activities and that they have been able to make a reasonable living income from the woodland.
As the law stands you are entitled to erect a small shed in your woodland (permitted development) as long as it is used exclusively for forestry purposes (tool storage etc) and not for regular overnight stays, recreation equipment storage or barbeques.
Other work, such as providing new or upgrading existing vehicle access onto a public road will normally need planning permission. You will also need planning permission if you are proposing a 'change of use' by using your woodland for non-forestry purposes.
More information is given in two recent articles from Smallwoods magazine-