Go 24", better (smaller) pixel pitch, better panels (generally).
There are a whole range of cheap 24"s now on the market, pick any one you choose really. TN + 24" is not a great idea.
If you can reach to £400, what that is in Euros I can't check as my broadband is shit and xe.com doesn't want to load - get the Dell 2408WFP, but make sure it's a revision A01.
If you can't stretch to that, there's a Hyundai for around £300 with a VA panel, failing that you're stuck with TN.
Jack where do you think you can find a Dell 30" for £500?