Also keep in mind the support hours -- if the host only offers support during business hours (which isn't too common now-a-days), it may be inconvenient for you if they are not located in the UK. Additionally, if they claim to offer 24 by 7 support but do not really offer it, you may run into the same problem. Also, some people prefer to have a host that is geographically closer to them, but it is all depending on personal preference.
Good luck in finding a host either in the UK or a foreign country!
I have to agree with everyone, the ping latency will differ depedning on how far away a server is from your location. However getting a web server located in Germany or the US, you wont see much of a difference because of how the backbones run between the UK, Europe, and the US.
So as long as you dont it hosted in like Australia, you probably wont notice to much of a difference. I would suggest you check out the offers section of WHT and see what you find.
Also many hosts will offer Ip's for you to ping, or in many cases their own web site is on their hosting servers, so that way you can tell how they will serve for you.
Response time really shouldnt be an issue to be honest, If it is infact for website only I cant see you having too much of a problem it might load slower, but the difference is going to be so tiny you wont notice,
So if your worried about how is cheaper or who has better support, depending what the server is going to get used for I cant see it being an issue..
just do research on the company first, see where their backbones are etc..