Create login via post code and limit page access

I have a great plugin running currently but my client now wants more! It currently does not display a webpage if your not logged in, but they now want it that if your logged in you can access certain pages, but based on your location. So people in the UK only get to see some pages. Where the rest get another page?

Can this be done?
Do you guys know of a plugin or a way to write a function to do this?

Thanks so much, wordpress changed our companies life 4 years ago and we cant thank you guys more!!