My broadband Internet router does not have any spare Ethernet connections that I can plug my Network OWL into

You can create additional Ethernet ports by purchasing a Network Switch such as the NETGEAR FS605 (http://www.netgear.co.uk/home/products/switches-and-access-points/unmanaged-switches/FS605.aspx) - this provides 5 ports.
You will also need an additional short Ethernet cable (Cat5 patch cable).

• Remove one of the existing Ethernet cables from the existing (fully loaded) router and plug this into any of the ports on your new Network Switch.

• Now plug the new Ethernet cable between this spare port and one of the other ports on the Network Switch.

• You now have 3 spare usable ports available on the Network Switch - simply plug your Network OWL into one of them.

Note the Network Switch must be powered.