I spoke to Daniel Staincliffe again, in a chance encounter in the studio at University. It turns out he's probably saved me some time, we're both trying to figure out the best way of having "a button" attached to a computer, in its most literal sense. One of my plans was to dismember a computer keyboard and try to harness the power of just one of the buttons - but Dan has tried this approach already and it is plagued with problems.
I suggested (another of my plans) maybe doing exactly the same but with a mouse instead, its much simpler inside and only has two buttons in the first place rather than 102 on a keyboard. He just said "Why didn't I think of that?" so hopefully it is going to turn out to be a good (working) idea. Fingers crossed, because if it doesn't work I'm going to be a bit stuck.
Action required, by me, to test it out!