Thanks DeSade, but there's a bit more to it than that.
For every other website, whenever I reduce the size of the window, the content stays where it is while the amount of it that I can see reduces - just like looking through a real window, you see less of the view with a smaller window. But with mine, you always see the full view, but with everything crushed together. To see this for yourself, go to www.ashleyhastings.co.uk and drag the window smaller.
Sometimes it looks a bit squashed together even when people open it in a full-sized window (as it seems it did for you). So tweaking the code to suit one persons view isn't going to solve the problem
Whether it's got something to do with the fact that I created the site in Word, I don't know.