I think I unfortunately know the answer but here goes.
I just about managed to keep blight away last year (with spraying) but at the end it took a few plants out (which I removed immediatelly).
Should I get rid of the border beds (plant pots only rest on the soil (plants not planted directly into soil)?
Thanks
My guess is no, though I'm interested to hear other more informed advice. My understanding is that blight blows in and doesn't over-winter, although I know opinion about that varies, but if blight spores do over winter I believe they do it on infected plant material rather than in the soil as such so if you've tidied up the dropped leaves and you're growing in pots I'd say that's clean enough.
Blight only survives on living tissue so is unlikely to have over wintered. As you are only growing in pots I would suggest you spread the old compost on the garden and give the pots a wash. Another serious disease you have to be aware of in tomatoes is Mosaic virus. So, no smoking in the tunnel or greenhouse. ;D ;D