I'm currently off sick with PND not returning after maternity ended. I'm currently getting paid full pay. A phased return has been suggested by my regional manager when I'm ready to come back. If I do do a phased return will I just be paid for the hours that I do or will I get paid for my normal contracted hours?
That depends on your policy/employer, and what your sick pay entitlement is. You should be paid for hours worked and the hours you don't work will be sick pay. That could be full pay, half pay, SSP, or nothing depending on how long you've been sick and your company's sick policy.
Are you having any meetings with them to manage your return? It would be worth having this discussion with them. I would assume that they want you to return to work so would be happy to answer any questions and reassure you.