Is the MAC address of my VM different to the MAC address of the host? My landlord provides my connection to the internet and they are changing their network which requires me to register my iPhone and MBA. The instructions require me to use my MAC address at some point in the process. I run a VM using Parallels and all my mail goes to MS Outlook.

Do I provide them with the MAC address from the VM (Windows 7) or from Mountain Lion? Might they be the same?
The VM will use a virtual MAC address to map to the physical device MAC Address.  Keep in mind that if you provide the MAC Address of the Wi-Fi Adapter from your MBA, that you're now locked to using that device for connectivity.  Thus, your VM will need to use that device as it's bridged connection to the internet.

You should provide the physical hardware MAC address to allow your device and your VM access to the internet.