You can't hunt without the landowners permission. At the moment there aren't many restrictions on air rifle ownership in Scotland, (although this is very likely going to change) providing the rifle has a power of under 12 foot pounds. If you want to hunt and have no land of your own you must make friends and gain permission from a landowner. Once you have a permission know the boundaries of the land and what the landowner is letting you shoot.
Legal quarry in scotland is,
Rabbits, good to eat but should always be taken with a headshot.
Hares, good to eat but quite big for an air rifle so headshots only.
Rats, shoot on sight, chest or head shots.
Stoats, pests but kill rats too.
Weasels, same.
Grey Squirrel, shoot whenever you can as he is giving nice reds the pox, dirty buggers
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All these are pests and may be shot at any time by te landowner or someone who has his permission. You can't shoot foxes or deer. They are too big.
You can shoot pest birds under the conditions of the "general licences," which you don't need to apply for but have conditions. For instance you must have a reason for shooting a bird, common ones are to protect crops or wildlife. Read the general licenses on the BASC website which is the british association for shooting and conservation. You should think about joining too.
Pest birds are,
Wood pigeon, good to eat and a pest, headshots or back.
Feral pigeon, good to eat and make a mess in barns, heart shots work but learn where the heart is, its only slightly larger than the head.
Colared doves, good to eat but small and often quite tame so I don't.
Rooks, branchers, young rooks that can't fly yet are good to eat, adults not tasty. Heart shots ok.
Crows and magpies are pests, head and heartshots are ok.
Jays and jackdaws are considered pests but I think they are characters, like adult rooks are and let them off.
You can shoot game too, with the landowners permission of course and when it is in season. Game are phesants, partridge and wildfowl. All these need to be taken with headshots and shooting pheasnts with your rifle isn't considered the done thing but if the landowner says you can you are ok to do so.
Learn what your quarry looks like, be careful with pigeons as there are stock and turtle doves which look similar to people not farmiliar with them but are protected. Buy the book, "Air rifle hunting" by John Darling too, it's full of good info.
Learn to be a good shot before hunting live quarry, kill zones are quite small on all the quarry so you need to hit a beer bottle top every time at your chosen range, which is no more than thirty yards unless you are a better shot than me. My father bought me an air rifle when I was fourteen but I wasn't allowed to hunt until I could hit beer bottle tops he put on fence posts every time, quite right too.
I hope you have been paying attention, sorry if you knew any already but you sounded a bit out of your depth, you can't camp anywhere you want, I might already be there
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I know of continental sportsmen who went to the other extreme and shot the wee birds, sparrows, blackies, robins, etc., using hunting rifles 
