Apols for drama of thread title.
So, it's my 1st proper growing season and I am obsessed. I've grown tomatoes before, but never had blight, but I think it has just struck. 
Is this blight? See attached pics. It's v v damp here, has been for weeks, although it's quite cold too.
If it is blight - what do I do? Pick everything from just affected plant, or all my tomato plants?
NB these are my home plants, I also have an allotment full of toms 1/4 mile away, on which some people had blight yesterday at the other end. I need to go there and attend to poorly plants too, don't I?