yer i was gona add 1.5mm 3 core flex for the drivers and plugs!.
also you might want to consider something like this to join the mains cables on the drivers -
https://www.amazon.co.uk/All-Pond-S...ocphy=1006669&hvtargid=pla-427894899058&psc=1
as for dimmers the choice in the uk is limited, your probs gona end up with standard 100k pots. like -
https://www.mouser.co.uk/ProductDet...MI6sLRocXU6QIViLbtCh179wDSEAQYAyABEgIyHPD_BwE
if you need absolute full power from your drivers you might want to get some additional 6 ohm resistors to wire to the pots as most of the 100ohm pots when checked fall a bit short like around 95kohm this would only give you 95% power from your drivers adding another 6 ohm resistor makes sure you get the full 100kohm.
you probs gona want a little box to house the dimmer and a nob for the top.