idea 1 - simply disable file and resource sharing on the laptop. others will still see it but will not be able to get to it unless they are determined hackerz
idea 2 - set up two access points/routers with different SSIDs, keys, and >>different DHCP ranges<<
idea 3 - set up static IP address on the laptop that is outside of the DHCP range set on router/access point
idea 4 - i don't really know what BT hub is and if you can manage it, but some routers allow setting up "guest networks", or have wireless network separate from wired. Look if you find settings like that, and connect the laptop via cable.
you are still going to have to isolate hosts at layer 2.