Mac and windows-how to purchase Win7

I have 2 days ago bought MacbookPro and Parallels as I have some software that is never going to be Mac OS (specialist language stuff). I have a number of previous machines with either Windows XP or 7 installed as OEM. The only surplus one of these is currently overseas and will be there until next year. I am a student and have access to cheaper upgrades for Windows but this assumes an original to upgrade from. i am in the UK so can't follow the instructions to throw money at MS for a new copy to get things moving, but neither do I have "bootcamp" nor an installation disk nor a previous version of Parallels - please can anyone out in MacLand help me, how do I go about getting a product key to install Windows as part of the Parallels installation? I am sooooo looking forward to being a Mac user after a few years of persuading the significant other that it will work with all our other hardware and this hiccup is not helping my cause
Absolutely any help appreciated to get me up and running so I can work over the summer,
Thanks guys
Mel

The only way to obtain a legal product key is to purchase it from Microsoft. Their online store is available from the UK. Access the store and purchase a full install copy of Windows 7.

No one is going to help you otherwise to obtain a key by any other means. Thread closed.