Thank you! I'm so glad you've enjoyed the fic - it's been a blast to write for Three and Jo and UNIT, and I get the distinct impression I'll be giving it another go at some point.

there's hardly any fanfiction featuring them

Are you familiar with Jeri Massi's page of Third Doctor fic (http://www.jeriwho.net/whofic/nindex2.html)? There's some great stuff there - extremely long and well-planned fanfic. It's a goldmine!