As far as I know there is no such thing as a UK M1. If there was the only different cables would be the addition of a SCART > Composite converter.
What outputs do you have on the back of your Sky Box ? If it's like mine then it just has the HDMI output and 2 SCART sockets. In this case you have 2 choices:
1. If you must stream HD you will have to buy an extra box that will take the HDMI signal, strip out the HDCP and output in HDMI for the TV and component video format (Red/Green/Blue) for input to the Slingbox. We know the HD Fury works (although it costs more than the Slingbox) and Sling have given their approval to a Chinese one. Check out Slingbox.com - Buy Slingbox Accessories (Although frustratingly you have to switch your location, top right of screen, to the USA to see the page).
Later: Just seen this as a recommendation: Amazon.com: ViewHD 2 Port 1x2 Powered HDMI Mini Splitter for 1080P & 3D | VHD-1X2MN3D: Electronics
Even Later: Just realised this won't work with the M1, it is only suitable for the 500
2. My solution: Accept you can stream only in SD, buy a SCART > Composite converter like this and use the Composite (Yellow) video input and the analog audio (Red/White) input