Hi there I have a gorgeous cat who is due round about today, Yesterday she had what you could only call a mucus plug, she is very restless and edgy, can't seem to settle for more than 5 minutes, or stay in her birthin box. Any advice what I can do to help her.

I you haven't had any experience with birthing kittens I would say take her to a vet.
Get her spayed as soon as the kittens are weaned if not earlier.

As for the actual birthing the common story lately is "I dont have enough money to take my cat/dog to the vet" so all you can do is watch her...
Make sure she is not having any trouble getting the kittens out and that she is removing them from the bags and cleaning them.

Make sure she is bonding with the kitens and not acting aggressive towards them in any way or you may have to remove them.
Cats can have kittens up to 24 hour apart so be prepared to be in for the long haul.