I've got that on but all I can see is the pictures I've taken on this iPad.
Go to iCloud.com on a computer and see if the photos are there.
When by setting up your iPad you didn't choose to restore from a back up, you will not be able to retrieve your photos. Your only option will be to restore your iPad to a backup. This will delete all your current apps and information from your iPad.
So, before you continue make a backup of your iPad on iCloud or on a computer.
Then restore to the backup of your iPhone 4, store the images in the Photos app on a different source like Dropbox or google Photos,
or enable iCloud Photo Library and wait till all the photos are uploaded. After you're finished restore your iPad back to the latest backup you made.
I hope this helps.
Yes I know it's a lot of work and quite time consuming, but it's up to you if the photos are worth it.