just one thing to add - the two switches could be incorporated in one off/on/on switch (like a side/headlight switch) so that you have off/on with headlights/on all the time positions. would save another switch position and having to remember which switch does what....
3 position light switch. replaces Lucas 31788.
Heavy duty with metal body and plastic toggle lever.
Switch body dimensions: 37x27 x31mm deep.
10A @ 12V, 5A @ 24V.
in the above circuit, common (to 86 on relay would be 4, main beam circuit would be to 6 and overide would be 8).