your only chance is :
if you have visited quidco that same day, and activated the cashback for WDTC but did not book. And then forgot to activate.
in that case, your first activation will show in the claims form, and you can try submitting a claim that way.
It worked for me last year, I had activated the cashback but had to go out, and when I came back I forgot to activate it again. I submitted a claim and it worked, but only because quidco had the trace of my activation within a few hours of the purchase
if you have not activated the cashback at all in the couple of hours before you made your booking, then you're out of luck.