can you ping sites using the FQDN??
i.e.. try pinging xrv.org.uk
If yes then try pinging bikelane.com
(gave you a UK based site and an american based site as that should check DNS and routing..)
If they ping OK then your DNS is fine if not then you know it's DNS issues.. Could be simple routing issues, we used to have problems with Orange and used to get stuff like american sites, or any site not in thier own cache go down quite often

One of the reasons as to why I moved to VM (and the fact that thier 40Gb FUP stinks)