Nope haven't tried it, but here in the US we can go to Adobe's website and just click the link for the version we want to upgrade. When you log in and go to check out you will get a link to talk to a rep in chat. I would say just ask if you can use the old code for the education version to upgrade.

I doubt you will save much since the education version is already deep discounted. I just checked the website and you can buy the full student version of photoshop extended for $199, where the full version costs $999.