Calico in penrith have 40mm vdl in stock most of the time. picked up the bits for my durso there.
Why do you need 2x end cap ( unless one is for spare incase you overdrill the hole) 3mm works but clogs quickly, if you can be bothered silicone in some airline and put a tap on the end.
EDIT almost forgot, don't glue the end cap just ptfe it inplace as you remove it quite often for cleaning. this depends on the length of your uptube. i kept mine short so you don't see it (hence the regular cleans)
1000 litre ecosystem, 3x400watt Metal halides,2x54 watt power compact actinics,125watt envirolight over sump,80kg LR (approx) Lyretail anthias, six line wrasse, rusty angel, 1 ocelaris clown, orchid dottyback, Rabbitfish, midas blenny, kole tang, sailfin tang, zebra dartfish, orchid and sunrise dottyback. LPS, clams and SPS 1000L ecosystem