WARNING: completely unrelated to words

I'm almost completely ignorant to the British governmental system, so I have a couple of questions. I turned on C-SPAN and they're showing Tony Blair answering questions in the House of Commons. It seems like they are quite uncomfortable. There appear to be more people there than there are in the US House of Reps and they look to have about half a meter of butt space. They also don't have individual desk space as in the US Congress. Are the two sides split basically between the Conservative and Labour parties? Why does the Prime Minister sit at the bottom in the middle of the others? He has to sit down and stand up every time another question is asked and it seems like a terribly inefficient system for discussing policy. I'm sure it's just a matter of custom, but why don't the free up the space a little? How can there be so many representatives in such a small country?