I do some very earlies in one most years - swift or rocket. Plenty of drainage holes in the bottom, along with some rocks/crock. I then put about a foot of compost, place 3 spuds on top, cover with compost by a few inches & earth up to a few inches below the top. Old tea bags get used as part of the earthing up & the lid is put on if there's a forecast of less than 5C.
Carrots work really well too - this year we did them instead of spuds & got monsters (in fact we ate a few this week), normally we follow the spuds with them & still get reasonable ones in winter.