I was in a similar position to yourself about 3 years ago; here are a few comments
Read and Surf the Net, including You Tube as much as you can; that will get you used to techniques and the jargon. I haven't been on this website/forum for long, but I can tell there's a helluva lot of information & advice here. I've just posted some ideas under the Resources section
The problem with leatherwork, like a lot of hobbies & pastimes is that you seem to need a load of kit all at once (and so need to spend a load of money!) But also you can start reasonably cheaply and simply, then carry on to spend as much as you want
As you read & Surf you will start to realise what you need to buy as a 'proper' tool and what you can make or improvise. In fact that aspect becomes quite interesting and satisfying. I have made or improvised a skiving knife, an edge slicker, a strop, a sewing pony, and I cleaned up a scruffy old craft knife to make a dedicated leather cutting knife.
If you have problems with your strength or posture, you can use a miniature drill, like a Dremel, instead of an awl
Most important thing is a decent desk or bench at a height that suits you, and where you can leave your work in progress, without having to set it up or clear it away each time you need it.
If you can afford it, Tandy's Hand Stitching Kit, product code 11189-00 has many of the things to start with, though you'll need to add a number 2 or 3 edge beveller fairly soon. Keep your eye on Tandy's UK website, they often have sales
Al Stohlman's book ' The Art of Hand Sewing Leather' is good, and is often recommended, but I think it's overpriced at about £15. It's included in the above kit, so you might as well put your money towards that.
There's always Ebay, but caveat emptor, and remember the UK version does not advertise knives
Try car boot sales & second hand tool stalls on markets. You probably won't come across a complete set of leatherworking tools, but there will be general stuff, and things you could modify
To save some money,
you could get just an awl blade and make your own handle
start off with a cheap snap - blade knife
I have heard of people making a stitch pricker from an old fork.
I made my skiving knife by cutting down and sharpening an old putty knife. It's not bad, even though I say it myself, as the old steel has taken a razor sharp edge
I would leave tooling, carving, and colouring for the moment. Do simple suff well, get the basics right first, and build up your experience & skill