Where have you got them? If it's too cold they won't produce shoots. Once they do, make sure they're kept in full light so the shoots don't get leggy before you can plant them. Remove all but 3 or 4 shoots before panting as this will give better crops.
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Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.
Some info here that may help - https://www.rhs.org.uk/advice/grow-your-own/vegetables/potatoes
6 weeks now but nothing showing
It could be too cold for them in the GH, they may fair better on a warm window sill indoors.