I forgot to mention that there's also the TV Player app, which is available on most devices (on Xbox but not PS4):
https://tvplayer.com. Allows you to watch Freeview channels streamed over the internet. There are also two paid for options - Premium for £6.99 a month which gives you access to virtual recording (10 hours), on-demand, no advertising, HD and extra channels like FOX, Comedy Central, SyFy and Discovery; and Premium+ for £8.99, which throws in more kids and foreign channels, along with Eurosport 1 and 2.
So basically no matter who you go with they're cheaper than Sky's base package of £22 and £27 (HD) a month.