14 is NOT too young. I started at 15, but wish I started sooner (16 now)
Starting sooner around here gets you past the laws about age and buying a knife.
I use a dremel on a regular basis. Good tool to have. I also use my drill press on a regular basis

another good tool. I actually use my dremel to polish the blades to an extent. There are rubber polishing wheels that I use, and that takes out the bigger scratches. From there I go to sandpaper. This method conserves paper and takes a lot less time.
To cut out the blades, I use a drill with 3" cut off wheels. This does it MUCH faster than a hacksaw. You could use a dremel with cut off wheels, that's what I started with, but that takes upwards of 2 hours.
If you can find cut off wheels for your hand-held drill (assuming you have one..do you?) and a mandrel, then you won't need the hacksaw. The price of the mandrel and wheels down here is the same as a hacksaw and blades.
If I were in your shoes right now, I would suggest the drill press. You say you want to make a butterfly knife eventually, and you will NEED the drill press for that. I find it much better just for a fixed blade also. My first ones I did with a hand drill, and the bolts got bad placement because of the bit 'walking'. The drill press is more necessary in the long run than the dremel.
I have yet to make a kit knife. All my knives so far have been my own designs made from scratch. I do have a kit here that I am about to make, it's a folder. I bought it so I could learn more about folders, because I plan to start making several from scratch. Fixed blades are relatively simple, as long as you don't try something really far out! I would just buy some steel, and start making your own from scratch. It's more fun than a kit, knowing that you did 99% of the work.
Do you have any steel yet, or any steel suppliers that you know of in UK?
Finally, READ! Read a ton. That is actually how I got started making knives. I ran across a knifemaking book at the library, and I started making 'em. The $50 knife shop is a good one to get you started, like Bladesmth said.
Hope this helps
~Brian
-my second knife, with help from these guys at the forum:
www.geocities.com/jagknives