Wondering the same. Half way through her pregnancy or is she delivering??
When you say "half way in whelp"...do you mean half way through actually giving birth?? Or do you mean half way through her pregnancy?
Because if you mean she is giving birth right now, and the pups are high, and there is no sign of them appearing after a few hours, despite her straining to produce them, or you see that she seems unwell in any way, then you need to get her to a vet a.s.a.p.
Access to veterinary care 24/7 if necessary during pregnancy and whelping should be a given.
Pregnancy, birth, and raising of pups can run into expensive emergencies without any warning. Sometimes "waiting until the vet opens or pay day comes around" can be too late.
It's wise to have a chat with your vet, and make sure any emergencies are prepared for....the emergency number (out of hours vet) on speed dial, or other arrangements made with the regular vet, in case either advice or a home visit is needed during the birth (whelping)
My advice would be to call your vet's office immediately for advice if you have any doubt about her well being, or the pregnancy or birth. I know it's Saturday, but on the surgery answer-phone there sometimes is a recorded message with another number to call in case of emergency. You could call to ask advice.