I think this is one of those riduculous situations where authorities don't really know despite enforcing the rules. You might get different answers according to how you present the idea or wether you get the correct person on the end of the phone.
My understanding is orchards are generally considered agricultural land. Woodlands are not therefore different rules apply. Therefore what defines a woodland? The nearest I found was here:
Forest commision
"The definition of woodland in United Kingdom forestry statistics is land under stands of
trees with a
canopy cover of at least 20% (or having the potential to achieve this), including integral open space, and including felled areas that are awaiting restocking."
That to me sounds no different from a potential forest garden, it also seems to be for thier statistics so I tried thier search function but got no furthur.
People sell stuff from there woodlands all the time but apparently it can be a bit weird grey area again as long your not heavily foresting it usually doesn't seem to an issue though.
Taking out things might be affected by stipulations for example wether its in a conservation area, wether any is ancient woodland and tree perservation orders. This sounds highly unlikely with the species you mentioned though.
Also if you do ask your LA I would not use the phrase 'forest garden'. They might have no idea what that is and consider that a garden. I think if you asked wether you could grow trees for timber and happened to sell produce on the side there would not be an issue. Fruit woods and nut trees good make good timber too and its not uncommon for them to be in woodland.
If you grew it all from seed it would also be hard to prove you even planted it.