Hi. Ive had trouble finding pipe and valves suitable to use in the uk but after much searching on 'tinternet I've found a few places that may be of use to you:
https://www.pisces-aqua.co.uk/acatalog/Plastic_pipe_and_fittings.html
http://cityirrigation.co.uk/acatalog/Solenoid_Valves1.html
http://www ...