Try a factory reset of the Smarthub by pressing a pin into the recess button on the rear for about 20 seconds. This can often sort out problems.
After doing that make sure you turn off "smart setup" on the Smarthub.
See link how to do that.
We will try that, the go live switchover is the 1st May, so it was using the old copper connection. My husband thinks it may be because my laptop is ion windows 8.1 but should that make a difference?
There is no reason to wait. The laptop should be able to connect regardless of what type of broadband you have.
Try turning off the 5Ghz wireless on the SH2. Go to Advanced Settings > Wireless and set the 5Ghz to Off and press save.
Using one of the devices that does connect, login to the hub management page and disable Smart setup.
Have you tried rebooting the device which won't connect?