I've never heard of this kind of requirement before from an accountant.  Almost every one I have worked with has both programs.  Are you in the process of switching to QB?  Why does the accountant need the file in QB format?

There is a conversion utility I believe that Intuit has but as far as I know it only converts the US version of Sage 50 and I believe you have to have both versions of the program on your computer to use it.

I would talk with the accountant again and find out why before you start trying to find ways to go about doing this if you are going to continue to use Sage 50.  There could be significant costs involved.