I Potato Blight It is looking as if this could be a year for potato blight

I think the problem with Bordeaux Mixture is the build up of copper in the soil if you use it frequently. But it won't harm bees, especially if you spray it in the morning or evening when the bees aren't active.
The only problem with Dithane 945 is that it is extremely harmful to aquatic organisms, from water fleas to fish, so don't spray it anywhere near a pond, ditch, stream or river.
I think you are right about potato blight. Even here, a good distance south of you, we are experiencing a lot of wet humid weather. Once the potatoes get it, it spreads to the tomatoes, so I shall be spraying very soon, much though I dislike having to do it.

My 'cure' for blight is the incinerator! I just dig everything up and burn the lot!

Thanks Bertie, your answere makes sense. I only have Cheshunt Compound in the shed to combat damping off but might use this on the potatoes. I don't want to lose the whole crop, Ian!!!!

give the garden some lime dont grow potatoes on the same plot for seven years try some cabbages etc next year on that plot

Blight blows in on the wind and falls in the rain, Kennyboy. So even a drastic move like you suggest isn't likely to work for long.
As for not growing potatoes for seven years!!! We'd starve or have to exist on Jersualem artichokes (a fate worse than death!)

No fartichokes in our garden, Bertie :-)