Ah its ok mate, think I sorted it. Put the SH in modem mode, waited for it to reboot, then turned it off for 2 mins and turned it on again with the router wired into the port nearest the main cable. The thing is, the speedtest I do is not very different to what I got from the SH in normal mode when on wireless. So its not really an improvement.
Its also created a guest network with a similar name to the one I gave to the router network and its open and unsecured, which Im not happy with. Any ideas?
At least it works, but I was hoping for higher speed tests scores.