Hi all, thanks for the interesting reads
As it happens, for all my "Let's get my knees ready!" action, I did in fact do very little on Wednesday. I spent a little time training, and looking at what the actual movements were that caused discomfort, and then talking with our secondary instructor, a nidan, and also a sports physiotherapist of sorts, I do believe.
From how I explained the problem and all, she basically assessed that it was more likely than not just fairly common knee strain. The fact I am a fairly huge guy is not doing my joints any favours!
Other than obviously trying to lose a little size (I weigh about 390lbs, but 'appear' about 170lbs less..), her suggestion was that I simply strap it up as best I could to give it a little extra support, and to perhaps speed up my techniques a little, and try to carry more momentum into my ukemi and rolls, so that although the same pressures would be applied to my knee, and yeah, it will be uncomfortable at times, the theory being that my knee will be under the strain for a lesser period of time.
Time to get saving for those prosthetic knees perhaps