I thought I would post an update just to let others going through the same experience know about my situation, now 21 months after the original injury, and to give a brief synopsis of my recovery.
I believe I was very lucky, in that I was in a cast for only around 6 weeks, after which I walked with a limp for a couple of months and was back on the dancefloor within 6 months. According to my physiotherapist I could have done so a couple of months before that, if I had wanted. So for me, luckily, the injury healed very quickly.
21 months on I am still very wary of jumping/leaping explosively, but in other ways am not affected by the injury. My left (injured) tendon is noticeably thicker than the right one, perhaps because I did not massage it as often as I should have done, but apart from that there are no noticeable differences.
I am glad I opted not to have surgery. I didn't want to risk post-operative infection. I also have a friend who received less than good treatment from my local hospital (and in fact died last year, partly through neglect). I also don't like the rather chaotic atmosphere there - it hardly inspires confidence.
Maybe if I had private medical insurance I might have opted to have had the surgery, but as a believer in the body's amazing capacity for self-healing, I also wanted to put it to the test.