In case anyone searches for this in future, I thought I'd post an update.
My hand has continued to improve day by day, as everyone said it would. Now, at 12 weeks on, it is almost, but not quite, back to normal.
The last bit to fix itself was my middle finger which, until the last week, had no sideways movement. But now, it has virtually the the same range as its opposite number on my right hand. My grip strength is almost back to normal but I notice that the pinch grip (forefinger and thumb) is still not quite as strong as on my right (non-dominant) hand - in doing a contest, the right hand always wins the piece of paper!
My handwriting is still worse than it was beforehand, but better than a few weeks ago when meeting notes really were illegible! The one thing that I still struggle with is left hand upshifts on my commuting bike (where the front mech has always been pretty stiff). but I expect that will come back soon.