Save yourself a fortune and go to Primark/Penneys and buy these:
https://www.katieelisabeth.com/2013/04/skincare-purederm-exfoliating-foot-mask.html
They're 3.50euro over here so probably 2.99 in the UK? And they are AMAZING. You put it on for 60-90minutes (I tend to put a pair of socks over them to hold them on firmly). After about 4 days all the hard skin starts flaking off. It's not pretty but after a few days when all the dry skin is gone you're left with feet soft as a baby's feet.