Just soft curls on the new foliage at the top?
If so nothing to worry about, if there is a little bug in a tight curl you've found the culprit!

Is the greenhouse getting to hot and the water level has fallen the toms can have the leaves turn and curl,

Im a great believer in early morning watering before the sun gets high and a mist spray early evening, plenty of ventilation through these hot nights and a weak feed every other day once the flower has started to produce the baby toms.

Cheers

Hi DAVE?
Since my first reply ive been out in the garden putting away my toold etc
now its been a really hot one here todat and i noticed one or two of my outdoor tomato's have the leaves rolled, and this im sure is because of the heat.