I'd personally get a steel string accustic rather than a classical (if you intend on playing anything other than classical music). Good makes of budget guitars include yamaha, fender, encore, etc..(though a name never guarantees a good guitar) It'd be helpful if you could get a friend or somebody who knows about guitars to help.

Without getting technical a couple of things look for are how far you have to press down the strings to reach the fret board (the action)- usually the closer the strings are the earier it is to play, how comfortable or bulky the neck feels, look for any signs of poor workmanship like blobs of glue, listen to how the guitar sounds etc... For £250 you should be able to get a guitar that you can plug in which may become useful later on ($300 is a bit misleading cause guitars are more expensive in the UK and you get a lot less for your money).

Another thing that you could do is look up reviews on a guitar on the web (as long as you take what people say with a some scepticism) e.g.
http://www.harmony-central.com/Guitar/Data4/

O and one last thing- always see if you can get some money of the price of the guitar cause they usually will (esp if you offer to pay in cash) and its worth asking for any extras e.g a strap, case, and plectrums.

Hope that helps.