bush/cordon tomatoes

I have two bush and five cordon tomatoes.The first time i have been successfull in gettng to the fruit stage. I have had them in and out my polytunnel. For several weeks now i notice some curling of lower leaves and yellowing of the odd leaf with a brown spot, am i going to fail yet again. some fruit is medium big but not red will these ripen off the plant.cold nights are here in roundwood do i need heat in the tunnel.