Hmm don't know if I can pay that much right now, bought 5 pairs of NMDs this month (including my Datamosh).
Might be able to you get your money back or a bit more from StockX or Goat. There's also Reddit or local FB group (This is all assuming that you don't know about these places, but I have...
I think what you have to remember is that JD Sports lists their sizes in UK. So if you're normally a 14 and go down to 13.5 for the PKs, then in UK size, you should get a size 13. UK 13.5 translates to US 14.