This is getting complicated
Not sure what telewest actually use ...
Perhaps a call to their hepldesk - before you spend any cash - would be sensible.
A modem requires a pc to make it work and will plug into the PC with a USB connector generally speaking a modem will only allow 1 pc to connect directly to the internet
A router connects to the internet without a pc - More than one PC can connect to the lan and either connect to other PCs on the lan ... or to the internet via the router
telewest say
Should have Network Interface Cards
If you don't have a free USB port, you may need a NIC (Network Interface Card). NIC is needed to connect the cable modem to your PC.
so I my guess is that you do get a router and not a modem.
if it is a router it will have a few (depends on model) ethernet rj45 connectors
http://en.wikipedia.org/wiki/ADSL_modem/router
http://en.wikipedia.org/wiki/RJ45
note 8PINS
Not to be confused with rj11 4PINS
http://en.wikipedia.org/wiki/RJ11
The Homepack extends a part (segment) of your lan to wherever you want it
you can mix wire (the best) wireless and homepack together on the same network ... depending on accessibility.
the router is still required in all cases ... to connect to the internet,
...... Semantics just sell virus protection ;-)