It doesn't say whether or not the Asus one is an IPS panel. Assuming it is, I'd go with that one because it most likely has a better warranty (12 months, whereas the LG doesn't specify one, but Asus are known for their warranties).
I can't really suggest anything with such a low budget, but for the money, I think this is the best monitor for the money, as the only monitor I consider better is made by Samsung and costs around twice as much: http://www.amazon.co.uk/dp/B009668YPM
You are getting screwed on that price in the UK, yes. It's about $550 here, so I'm assuming the contains the VAT tax.
Edit: From the PB series, this one is a 23 inch monitor that's only about 27 pounds out of your budget. It's an inch smaller, but would probably look much better than the other two.
Console war in a nutshell: http://imgur.com/xA6GJZ9