Thanks for the reply
I'd already tried that - the only difference it made was that by unchecking the remote gateway, it allowed me to browse the web. Made no difference to trying to web browse to something on the remote network.
It's so bizzare, I can RDP, etc to servers, it just appears to be HTTP/HTTPS.
I'm due back in the office in a couple of days, I'll check with my colleagues just to confirm all our settings are the same.