you could try having a word with your local council see if they have a map of local authoraty land in need of manegment. (or enviromental/forrestry agencies) where I live in wales it's kind of odd, the land around the towns and villages (i.e the mountains) actually belong to the people who live here (got that in writing from the welsh assembly) while the plantation forrests (spruce/larch ect) are owned by NRW (national resources wales) while the natural ancient woodland belongs to the people.
many local authorities actually have large plots of land that they have no use for and are looking for people to take on manegment orders of the area which basically just involves keeping the area clear, waring them of dangerous trees so they can come and remove them and stuff like that (usually they limit premissions at first but once they get to know you they will open it up to allow more activites. just don't expect to be allowed to fell trees or have fires straight away)
the group I work with has been jumping through all kinds of hoops to get access to patches of land for setting up sustainable community businesses (logging of the non native larch forrests, replacing them with coppiceable/edible woodlands, ect) we had some trouble at first where the top level managers were all "yes you can have all the land you want we're all behind what you're doing" while the lower down local middle managers did everything they could to stop us.... turns out is was because the mid level guys had gone and sold the trees to a logging company. but now things have turned around, and just yesterday the guy in charge of the group went to survey a large plot of land given to us by NRW with plans to start developing it in the next 12 weeks.
on a personal level I don't see any problems with someone going into a patch of woodland and practicing bushcraft skills I used to do it all the time growing up. so long as you don't cause too much damage (heck felling a few trees can actually help promote growth and bio diverserty in densly packed woodland) and a lot of woodlands in britan are either coppice woodlands (which can be identified by multiple trees growing in small patches right next to one another) or plantation forests (usually of spruce, larch or pine) planted for the lumber industry which means they tend to be dense and lack ground vegetation and animal diverserty
this past month I've probably felled more than a dozen trees, (granted most of those were because they had died due to how dense the woodland is thus had become a danger while other's were simply to clear the area and promote growth) the felled trees were used for firewood at various events, used to make brash piles, make camp equipment for the work camp and various other jobs so none of it went to waste, granted my group has a maintenance order on the local woodland with premissions for felling (which took a lot of work with NRW to allow them to agree to it)
This site is "BUSH CRAFT " NOT survival the aim is to gain and use your skills and knowledge in the bush {woods} in the UK USA etc and to co-habit with Nature RESPECTING all things Trees, wildlife .You enter with the basics SHELTER, FOOD, WORKING, TOOLS etc AND LEAVE as you entered not damaging anything using only DRY dead wood .SURVIVAL on the other hand throws all that out of the window for the short or long time you need to SURVIVE!!!!!!!!!!!!!!!!!!!!!!! ! TOO MANY PEOPLE ON HERE THINK I NEED TO GET OUT HACK AND SLASH BUILD HUE SHELTERS to then spin the yarn, as some people said there are groups formed in regions of the UK to support this teaching technique to pass on the survival side of bush craft but all so to limit the FOOT PRINT left by us..On closing if you approach a farmer of land owner and explain what you plans are i`m sure they would accommodate you
actually if done correctly hacking and slashing (as you put it) can be benificial to woodlands. especially here in the UK. lots of woodlands were planted after WW2 and were intended to be coppiced and maintained on a rotation (7-35 year intervals depending on the wood) but have instead been left to their own devices, thus they tend to be densly packed resulting in lack of ground vegetation, limited biodiverserty (many once common animals have become rare due to the lack of manegment of woodlands) regular thinning of densly packed trees, coppicing and other techniques can be used to both provide useable material for practicing skills and for improving the biodiverserty of the woodland
