Those that have mentioned keeping livestock - what would be the end goal behind that? I'm assuming pigs could be sold for meat, is there much of a market for goat or deer? Coincidentally the woodland on the opposite side of the valley to us has a heard of goats in it, have never thought about what they do with them though. Would livestock have an impact on wild camping, I have visions of campers being attacked by pigs! Or pigs being let free and running riot!
As FYGT said you could charge a small fee for stalking deer IF the herd will sustain it. More likely the deer would be for your own consumption.
You guessed the market for pigs but only profitable if you maintain a larger herd than you likely want. However that does leave them for your own consumption as well or if allowed to go feral you could possibly charge a stalking fee for that as well (somebody here on the forum needs to advise on the UK legalities concerning that enterprise please) Be advised however that hogs can be destructive to land and other wildlife if the population gets too large.
There are two different types of goats:
1. meat goats and 2. dairy goats.
I have no idea what the market value for them would be in the UK but the market's growing here due to immigration trends. As always you can always keep the herd small and use for your own consumption. One of the advantages of keeping goats is that they'll keep the underbrush in check. That can also be a disadvantage depending on your ultimate goals.
I keep pigs for my own meat pays for it self and give me low cost very high quality Pork /Sausages bacon etc
and no you don't just release them into a wood you would never catch them again
Deer would be naturally occurring and you can charge a reasonable amount to lease the shooting rights to a stalker depending on whats there (may not be any) 30 acres isnt massive
if your going to manage the woodland you may need to Control the deer any way they like young trees etc
its a good source of meat if you do it your self etc or the odd one to do a deer skin and butchery course followed by Tanning the hide etc
ATB
Duncan