i have tomato blight in a polytunnel,,help me get rid of it please..

You have little chance of control over the blight. Pick in good fruit. Although green, store in the dark. As often said on GOY place a ripe banana in with them. I used to ripen mine in the applestore over the top of ripening apples.

The cahnces are you will get it next year too as the blight spores are now in the soil and get washed and slashed around by watering. You can buy blight resistant varieties.