[Ian_A]

Some of the leaves on a couple of the tomato plants I have in the greenhouse have curled a bit and have some brown tinges to the leaf. They were like this last week and it doesnt seem to have spread as those leaves haven't got any worse and the other leaves are still normal. Does this just happen sometimes? Possibly the temperature fluctuations with the cold nights then warmer nights and days...hopefully not a serious concern

[Ice]

Hard to say without a photo.  Leaf roll is nothing to worry about if the leaves themselves look healthy.  Don't know what the brown tinges are without a photo or a better description.  Do you ventilate the greenhouse during the day?

[8doubles]

Do you have any shading in the greenhouse as the plants could be getting scorched.
I find lining the house with bubble wrap diffuses the sunlight and keeps the plants warmer on these cold nights.