Posting in the hopes this helps someone.
I was concerned that my internet had slowed significantly over the past few days and had even disconnected entirely once, but reconnected after I turned the router on and off.
Figured it was due to the time of year, but then thought - hang on, why should other users outside my household effect my speed? Well it turns out they do, in the form of 'interference'.
What I did:
1) Went to this speed checker page to ensure it wasn't just in my mind http://www.uswitch.com/broadband/speedtest/
Confirmed my speed was running slow, only 4.4mb/s when it should be up to 8mb/s
2) Went to the knowledge base on Sky's website and found this Help page here:http://helpforum.sky.com/t5/Broadband-Setup-Connection-WiFi/Slow-Wireless-Connection/ta-p/581920
3) Printed instructions (because it turns off your internet momentarily)
4) Followed instructions - took 30 secs
5) Reconnected to broadband - you'll need your connection password so have that handy
6) Retested connection, and hey presto, now up to 5.5mb/s
7) I may test the other channels listed to see if they are any better8)
Also, i see you can 'repair' your modem if you have an ethernet cable handy, you can reset it, but I'm not sure if that will have an impact on the speed - has anyone tried this, can they comment on effectiveness?
Any other tips for boosting connection speeds appreciated!