How do I upgrade to ultra HD?

[AJRobson]

When I login to my sky I can't see anything to allow me to upgrade to 4K, earlier I saw a deal saying it was free for two months then £4 a month.

I've got a new 4K tv coming tomorrow so I'm looking to upgrade I guess I have to call sky I was hoping I'd be able to upgrade online.

I will need a new Sky Q box as mine doesn't support 4K can someone tell me how much I need to pay for a new box? 

[PandJ2020]

You'll need to call Sky to upgrade your box (and you can discuss UHD at the time).

All boxes are lent for the duration of your contract but they are likely to charge at least £50 to swap your box.  (Remember to remove your viewing card if you swap and you'll lose all recordings)