These just push on...
"Speedfit fittings have been designed for use with both plastic and copper pipe. They have been approved by the Water Research Centre and are within the requirements of the UK Water Fittings Bylaws."
http://www.choiceful.com/choiceful-id-20628-Speedfit-15mm-Coupler.html
Most DIY stores and Plumbers merchants will have them
Peccavi, March 2009