Either of 2 things:

1. "I have UK Homechoice, the laptop just plugs into the set-top box." might be the configuration to allow outgoing thru the unit.

2. UK isp's are reknown for blocking or shaping p2p sharing programs; see the UK link at point #8 at the bottom of the 1st post here ISP's known to BLOCK or Filter p2p or specifically Limewire. Ukbobboy01 would have a good idea of which UK isp's shape or block p2p. Some do it only during certain hours of the day (peak hours.)