Anti collision light must also be on in US if helicopter so equipped.
I also fly with position lights on, however this is because they come on automatically with the 2 secondary fancy little LED anti-collision lights, which are fitted to the H/Stabilizers, they look so pretty (flash, flash). I also fly with the pulse light system operating - alternating between landing and taxi light - again very pretty (flash, flash).
I operate both these lighting systems from just before I'm ready to lift until I land. This gives people on the ground or in other helicopters a signal that I'm about to move. As far as in flight is concerned I keep them operating, every little helps even on sunny days, and also because I don't really care how much they cost to replace (it’s a bulb!). 45quid may be a little expensive though. As far as the panel lights are concerned though, I don't usually operate these unless I need them. Possibly the helicopter you are flying, has the position lights and instrument lights connected together. I have personally never come across that.