Every year is like that here, so I start most things off either indoors, in a heated propagator, or in the polytunnel. Most things catch up with The South eventually and we do get crops - usually. There was one year when we lived in Edinburgh and had a couple of allotments, when we had a sea fog which went on for over a month - most crops rotted or failed to grow, but most years we get something, although we never get everything.
I suppose I have the advantage of expecting the weather to be rubbish so I am prepared for it, whereas this rain has come at completely the wrong time for you guys further south. I hope it improves soon.