Tomato Plant Problem

Couple of possibilities to check out. The first is red spider mite. You need a hand lens to see them, but often the plants look as if there are spiders webs on them. OR. It could be somwe sort of nutrient deficiency. For the first you need to spray with tepid water on a regular, like twice a day and for the second feed with a balanced tomato plant food.
There are other things which might attack, but I would need to see a close up of both sides of a leaf to help.

It is usual to stop them after 4 trusses anyway so they put their energy into the fruit.

Looks like to much heat - keep greenhouse cool dampen down with water on the floor to create humidity open windows and let air flow through – but not drafts - the give away sign is the curling of the leaves