Load mixing

[SomersetSammy]

I'm building a garden room that i'm thinking of making solar-powered (the load will be light - laptops, lights etc) with a battery bank and inverter for 240V supply.

My question is - i am installing LED lights and could make them 12V so they feed directly from the batteries or 240V fed from the inverter.  Is there any advantage to mixing 12V with 240V or is it just as efficient to run everything at 240V?  (i would have thought there was a small benefit as less power would go through the inverter running at less than 100% but may be wrong).

Many thanks for your thoughts.