I've got the insert for the MDPE pipe. THe stop tap is brass and has a brass olive which would normally be crushed onto copper pipe to seal. It's designed for MDPE, but I presume I don't do it up as tight as with copper so that the olive isn't deformed and it will be okay?
This is the stop tap:
http://www.screwfix.com/p/poly-stop-tap-22-x-25mm/60745
This is the stop tap:
http://www.screwfix.com/p/poly-stop-tap-22-x-25mm/60745