Stupid question! How do I move my photos from BT Cloud to my iCloud?

At the present time, you would have to download them to your Mac, then sync them to your iPad by selecting the folder on the Photos tab of your iTunes sync settings and syncing. You would then have to create a shared album (stream) on your iPad and add the photos to it, as explained here: http://help.apple.com/icloud/#/mmc0cd7e99 and the shared stream will upload a somewhat lower resolution version of the photos to iCloud (optimized to be viewed on an iOS device). You could then sync the photos off your iPad with iTunes by unchecking the folder and syncing, and view them from the shared album. You would want to keep the full resolution originals on your computer, however as the ones in the shared album (stream) will be lower quality.

Later this year, iCloud photo library will be introduced allowing you to keep full resolution versions of your photos in iCloud if you update your iPad to iOS 8 (it's available now as a beta service in some areas. (It's unclear if they will add an iCloud photo library icon to iCloud.com so you could just drag and drop them there from your computer.)

You're welcome.