Hi is it possible my bitch will still concieve although the stud was unproven this is his first time and there was only a slip mating no tie?

The slip would normally have Had to last at least a minute, but yes pups can result from such matings.

It is unusual in my breed to get a litter from a slip, but recently a lady got quite a shock as her bitch had not waned to stand and all they got was a brief slip.  two months later she thought the bitch had Pyometra when she started getting a discharge, and she produced one bitch pup which is what she had wanted, so she was happy.