Where to start indeed. You've picked a massive subject, but a good one. The situation you mention would seem to me that you want to learn hunting and trapping techniques along with foraging and gathering of wild fruits, fungi and edible greens and roots. Again, a big subject!!!
At the moment, you will find it difficult to address the greens, and fungi are just about over, if not already in your area, so that will start again in the new year for you. In the meantime, winter brings its own skills that you can practise. Snow covered ground helps in starting out in the tracking world, prints are clear and you will get complete prints that will make it easy for you to identify the animal that created the sign. Wing tips leave marks in snow when birds land and take off, which can be quite interesting to look out for.
If you have acces to some stinging nettles, try making cordage from them. This could be used for snares if required and if you couldn't get hold of wire when the proverbial hits the fan. Of course, animals could chew through these sort of snares which means you would need to check them more often than a brass snare. Also, search this site for the legal aspects of snaring, it's not quite as you would expect it to be. Spring traps are out, so you can't bend a sapling over and attatch the snare to ping little bunny up in the air, but if society were to break down, I suppose it wouldn't matter. You can practise spring traps I suppose, so long as you don't use it to catch anything, so once it is made, strip it out again.
Hunting, what are you going to use? A rifle of some sort would be ideal, bow hunting is not allowed in UK, but again if law and order broke down.....! Maybe you could give bow making a try, there are plenty of members who can give you advice on that. Also, maybe learn how to shoot a rifle, it's pretty straight forward but what you want is consistency in your shooting. I've no idea what access you would have to a shooting club, although air rifle clubs would be a good start. An air rifle would bag you small game, squirrels and rabbit and the like. Don't shoot birds, you may get in the proverbial!! Not too sure on pigeon and the like though.
If you wanted to start sleeping outdoors and creating fire (a massive subject on its own) you will need to bear in mind the law in UK. Scotland has different laws with regards to fire lighting, a much better way of camping out really. England is a bit more restrictive with permission needing to be sought from the land owner. Once you get that permission, keep on the land owners good side. It's down to that proverbial thing again, but this time it includes your doorstep, you know the saying!!
Finally, I'd stress the importance of safety. A basic grasp of First Aid techniques will stand you in good stead, you're gonna be using sharp objects and be playing with fire. Know how to deal with cuts and burns correctly, but more so know how to avoid them!!
You'll get cut or burnt now and then, nothing serious but it will happen when you get a bit cocky, it happens to us all!! And enjoy yourself, when you are out doing what interests you, forget about worries at home or at work. It is your time to enjoy and learn in the great outdoors, it's better than sitting at home watching crap TV!!!!
