If you don't play FPS games and have £300 max to spend on a monitor, then I would suggest the
Dell U2412M. This is a 1920x1200 E-IPS panel monitor and a really nice bit of kit (
here is a review).
There are a few 27in 1080p TN panel monitors available for under £300, however the image quality of these monitors isn't up to the Dell U2412HM with it's accurate colours and wide viewing angles.
One other option is to go for a 1080p 32in S-IPS panel TV like the LG 32LD450 (please have a look at
this thread). I have one of these which I use as a second monitor and for gaming - and it looks fantastic. This particular TV has a fast response time (so little ghosting) and very low input lag for a TV, plus it can be colour calibrated very well (even using one of the profiles mentioned in that thread produces a very nice image). If you are having trouble finding the 32LD450 then the 32LK450 is basically the same TV, just this years model. If you go down this road, then I would suggest making sure you get the version with the S-IPS panel (as opposed to the MVA one) as it tends to do better in games with less ghosting (though the blacks are deeper on the MVA).
if i went for the lg how would i know im getting the S-IPS screen just looked at a couple on lin e and neither says ,,unless i just cant see that