Blight is the bane of potato growers (and tomato growers) but The British Potato Council's Fight Against Blight and Blight Watch are two websites, aimed at commercial growers, that report outbreaks and near misses by post code, alerting growers by email or phone text message.
Volunteer local 'blight scouts' monitor humidity and temperature data passing on warnings of conditions that favour the spread of blight spores.
OK. So you've got to register as a grower (though there is a category 'other' on the drop down list)but the site does have a useful factsheet (click here) for gardeners from Garden Organic on how to deal with blight.
Worth a look at least.