Possibly but the big variation in temperature may be the cause 0c is very cold for them

Hi, welcome to GoY, cucumber's, {cucumis sativus}, is a half hardy annual, usually grown in summer, in a greenhouse , {or poly tunnel}, and do best when a temperature of 71 deg f can be maintained, although some varieties can be grown in a cool greenhouse, or cold frame, but will generally produce less fruit.
Whereabouts are you in the uk, as 20 deg c in the daytime, at this time of year is well nigh impossible without some sort of heater.
I think the best thing you can do is get rid of them, as they're past their best, and will not come again next year, I don't think it is lacking any nutrients, just past it's sell by date, Derek.