To add,
I started and then I stopped. My fund of course continued.
When I started it was on the basis that I would take out an annuity when I retired from the RAF at 55. In the event I didn't retire then and by the time I did retire the FSAVC rules had changed to that of the normal AVC.
This meant I was no longer required to buy an annuity at retirement which had the advantage that I would not be paying 40% tax back on the proceeds. The taxman giveth and the tax man taketh back again.
Now I have to take out an annuity before the age of 75. The downside of waiting of course is that annuity rates have fallen along with everything else. Now I wait.
Would I do it again? Yes. Would I have stopped? No.