If you have to plant them now, then you will have to do it though you may well be taking a big risk of course. After planting, you could mulch around them with a light compost and perhaps a very loose covering of straw. This can be easily removed when you get back.

Plant them a little deeper than usual, cover with a large inverted plant pot held down with a cane through a drainage hole.

These are interesting replies, i'm glad you asked this, Googie !

I've not grown from tubers before and when i bought some recently, the directions said plant from March onwards .... is this a bit optimistic then ?
I've planted one of them out but the others i've still got to get round too !

As much as anything its the wet and the cold.

Forgot to mention, surround the plants with slug pellets or beer traps!

or plant them in large pots and leave in the shed/coalhouse. when growth showing and weather milder plunge the pot into the ground and then easy to lift in the autumn to overwinter them.