Me and my dad share the same Apple ID and I want to set up his own one but how will he get all his photos contacts etc from my Apple ID ? Or will he lose them all? or could I keep them backed up for him and send the over via an app of some sort?

Have him create an Apple ID here -- Create and start using an Apple ID - Apple Support, then the both of you can create a photo sharing album -- iCloud Photo Sharing - Apple Support

Once he creates an Apple ID of his own, he'll have to start from scratch. If he has an Apple desktop or laptop, perhaps you can log into to your Apple ID on one of those devices, transfer what you need to a folder on the desktop screen. Then after he can log in (after you log off), and you can help import those items.

Try turning off syncing, then sign out of iCloud, and sign back in with the new Apple ID, then turn syncing back on.