We gave up on freesat when our old sky box (being used as a freesat box as I had long since cancelled the subscription) gave up the ghost.
At home I moved to plusnet when O2 wanted to sell my soul to Sky.
At work we were also on O2 and for now have been forced to continue with Sky's broadband. It sucks by comparison to O2 - we've had to do all sorts of traffic shaping in house in order to be able to make the thing work at all for us.
Meanwhile I wouldn't recommend Virgin Media from my recent experiences of trying to get them to replace the Sky broadband in the office with their 50Mb broadband service.
Whilst I have no time for Sky, for some people it works well - soo... if you're sure you want to cancel, great. If not then I reckon if you went through their customer retention people you would get a free replacement sky box and a discount - tell them you're moving to Virgin Media.
I've never used the Chromecast or the Pi or any of those other TV attached smart devices, but my guess is that unless you're an avid watcher of TV they will gather dust

I was thinking of getting one so that we could use Netflix on our big TV but as we only use it for movies and then only once a month, not sure I can be arsed (vs telling one of the children to make it work with a laptop

).