...based on the NHS website it might be thrush? She is feeding ok and my nipples are not sore.
My GP will always see babies same day: it will be ok to wait till Monday if she's in no pain and feeding well? Our local "out of hours" is at the local hospital and chock full of drunken undesirable types by 3 pm Sat! With a long wait.
Of course if she starts to look pained I would take her. 