I have spent some time on the internet regarding tomatoes and was quite surprised to find them growing in Greenland and Siberia. There they have developed plants that grow very quickly.
This year I am trying 'Stupice' and 'Sub Artic Plenty' which should bear fruit in 60days, from transplanting.
Otherwise I am staying with 'Tamina', 'Harbinger' and 'Alicante'
The question was - are they blight resistant, and don't suffer from blossom end rot", not "what are you growing".
They may not be blight resistant, but short season varieties may be an option to harvest before the onset of late blight (depends on the weather of course if early summer is wet then ...)
Koralik cherry is supposedly hardy and "late blight resistant", Fantasio F1 (or Phantasia - depends on where you buy the seeds) as blight tolerant, with Latah, Glacier and Alaskan Fancy as 3 other "short" season tomato varieties - I've never grown any of them so can only go off the supplier blurb. I have grown Ferline F1 and Legend which are often the 2 main varieties sold as blight resistant - I would agree that they are not blight proof but I would say that when compared to other tomato varieties that succumbed, they managed to keep going a good week or more longer which was just enough time to realise all was not well and get the fruits picked and ripened indoors. The Ferline was more resistant than Legend. Taste wise I found both were fine for making passata which is reduced down and concentrated (I don't like raw tomatoes so can't comment)
Blossom end rot - already mentioned about the calcium deficiency and irregular watering.