I ended up getting a Sony Vaio P. I've long wanted one, and they've dropped to a reasonable price. Doing some research beforehand, I noted that some of them were quite slow at things like video, so I stuck together list of stuff I wanted and what I would pay for it. I didn't want to exceed much more than £200:
Vaio P £120 - Just for the basic unit, I figured if I was patient, I'd get one for this price. I was checking one out at the weekend that went for this price, but with a cracked screen.
Win 7 £40 - A lot of the older models come with Vista, and it was reported that Windows 7 made a large difference to speed, battery, and processing
SSD £40 - An upgrade to an SSD should make a significant difference to battery life, even though the capacity isn't much different. I've seen the very latest ones going for £400+ with a 128gb SSD and the fastest CPU (1.8ghz atom), but that's too much for me. The newer ones do look slightly better too.
CPU £40 - I figured that if I could find one, an extra bump up to a 1.6 (from 1.3 basic)ghz CPU would be worth the money, as it would be very difficult to upgrade. I know what I'm using the laptop for, and a 1.6+ will do exactly what I need.
Extended Battery £40 - TBH, the one I bought, I didn't check that it was an official battery, which is more expensive and doesn't require a BIOS upgrade to function correctly (indicator etc). But seeing as the regular supplied battery only gives 2.5 ghours battery, the 5-6 hour extended battery is pretty mcuh essential.
Well, after all that, I found one with everything except an SSD within that range, so I bought it up. It also comes with a case and an extra (2 pin) charger (if it works), which will be useful for work, and the original battery. It also came with a 1.8ghz CPU, which is as good as it gets.
I'm a bit wary of spending all that cash considering my looming living conditions, but I don't think that's too bad, not only for a laptop, but one I've wanted a while and researched properly beforehand. (it was £255 inc shipping)