I looked at my one tomato plant in my greenhouse today, and was surprised and annoyed to see signs of blight - so early in the season, and after so little rain. So I decided to try mixing a garlic spray. I used most of the very small garlic cloves from last year's harvest, mashed them with a pestle and mortar, and followed the instructions - halving the quantities. I still have over 2 litres of the stuff left, and the recipe says it must be used fresh! Also my house stinks of garlic!
Whether it will deal with the blight or not remains to be seen!
16th June: It Works! After removing a couple of slightly blighted leaves and spraying with the garlic, there have been no further signs of blight! Next question - can the liquid be frozen and keep its fungicidal properties?