Think that if you pull the dipstick tube out, then the remains of the old stick will drop into the sump and not come out with tube, This in its self is not the end of the world as its made of plastic and should not cause any problems and just lay in the bottom of the sump for ever but if your really worried then drop the sump off and remove it from the bottom of the tube.
Don't think there is a seal present according to service box (interference fit) but if there is then put a small "O" ring on the tube.

This by the way is a very very common fault with plastic dip sticks on Peugeots

 

As mentioned before. There is really no harm in leaving the broken part of the dipstick in the sump. If you are going to remove the sump, then you would also need a high temp black silicone sealant. This sealant is used as a gasket when refitting the sump pan back onto the engine.

Adam

 

Hi John and Adam, thanks for the replys, I just didn't want to lose any oil after refitting the pipe back on, yea from what I read it's very a common fault, once I've removed it I'm going to keep the old one in just incase it happens again, and keep the new one in the garden for oil checks

 

If you can still feel it, is it worth putting a dab of superglue on the top half to try and draw it out? The break itself shouldn't be oily.