You've posted in the V6 forum, so assuming you do have a V6 box and not a TV360 box then try using your remote and clicking on Home > Help & Settings > Help > TV Care > I'm missing some channels and allowing around 10 minutes or so to update.
How did you add the Sky Sports UHD channels?
Changes made over the phone are usually actioned immediately. However if you used any other method then I'm afraid you might be in for a bit of wait for the upgrade to be processed.
Once you've agreed to the terms and conditions for any online renewals or regrades made through My Virgin Media or via an email offer that was sent to you, the orders go to a back office team who apply the deal. This can take up to 14 days to process and they'll send you an email confirming the change has been made. In this case then once it's been 14 days, if the new contract/channels hasn't been put in place, pop back and update this thread and a member of the forum team will be able check things further for you)