@AshleighJayne12
You can select to receive your phone calls on your iPad and iMessages will be received provided that you use the same Apple ID on both devices, but you can't have the same number on 2 sim cards.
I have no affiliation whatsoever with O2 or any subsidiary companies. Comments posted are entirely of my own opinion.
This is not Customer Service so we are unable to help with account specific issues.Currently using:
Pixel 7a (O2 & Lyca), One Plus 6 (Sfr), iPhone 12 Pro Max (Vodafone)