Put a set on quickly last night, just 1 on each side about 1/2 to 2/3rds from the top, quite surprised at how well I had been doing without them on. Setting the spinny normally and looking up and telltails are flying nicely. Quite surprised at how wide a band of tension you can have on the sheet before they really start to not fly though ?

I seemed to have adopted the let the sheet out until the luff starts to fold and then on with a bit of tension and the woolies are flying perfectly. I would guess though if you are new to the game then working the other way, getting the woolies to fly would be more indicative and quicker to learn.

I think Scarecrows suggestion of putting 3 sets on though is very valid as I have no real idea whether the lead angles are correct. Next step.

Thanks for all the info guys.