If you have a TiVo or V6 then migrate to a 360 and a Stream. You don't want a coaxial cable running into a garden due to possible signal issues.
Also best to dig a trench, minimum depth of 0.5 metres (500mm) with separate conduits for exterior-grade cables, meaning steel wire armoured (SWA) cable and direct-burial grade Ethernet Cat 6. Inside the garden room you should terminate the SWA cable into a consumer unit (CU) or a large fused connection unit (FCU) and the Ethernet cable inside a keystone jack or surface-mounted back box (faceplate). You need a qualified electrician to do the connections (but you can do the trench digging and cable laying yourself).
I recommend a gigabit network switch with at least four ports so that you can plug in a Stream box, games controller, wireless access point (if Wi-Fi from hub is poor), etc.