I need to replace the stop tap entering the house. The water main pipe in is black 25mm MDPE into a concoction of fittings to a 22m stop tap. I would prefer to fit a direct 25mm to 15m stop tap (poly stop tap?) with a drain cock above it into the existing 15mm copper tube. I have not had to replace any fittings on MDPE pipe before, although I have done extensive work with copper fittings. Can anyone confirm the basic points to watch out for, i.e. I think I need a 25mm MDPE insert, and lubricant as well as the poly stop tap, but there might be other factors to MDPE fittings I need to know. Any help would be much appreciated.