Hello all, thought I would write a bit of an update following the helpful responses I got to my previous post asking about the value of Tai Chi.
I did go along to local classes and found that I was far more tottery than I had thought! couldn't manage to synchronize the hand and leg movements and was frequently in danger of over-balancing. That convinced me it was something worth pursuing, as the exercises should help to strengthen and improve balance.
I can whole-heartedly endorse what some of you told me: the teacher's style/method is very important. I found the one I'd picked very gentle in approach but (for me) not focused enough on helping class members to work out the detail of the movements so that we could replicate. On the other hand, he was very definite about not over-stretching, etc, and stopping/resting when needed. I also found that the sessions left me feeling very (pleasantly) tired, but oddly also quite energised.
I've now bought some dvd tutorials and have decided to continue practising in the comfort of my own home. I can already see an improvement in my balance, and the tiredness that follows is good because it's not the result of stress. Many thanks to all of you who gave such helpful advice.