I have an Ipad pro with Sim. If you are an O2 phone customer you should have already registered for O2 priority on your mobile. That being the case all you will need to do is download the app from the App store and log in using your user name and password.
Ipad will not receive standard Txt messages but will receive Imessages(messgaes from users in your phone book that use Iphone).
I set up mine very quickly with no issues at all
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