Fair enough. As I said, I wondered if you were perhaps talking about 4W ~36W tubes, but clearly notThese are what I've got https://www.toolstation.com/shop/Lighting/d220/Batten+Fittings/sd3342/LED+Batten+Fitting/p54130 6ft 65W 7800lm each, garage is 30m2 so 1040lux. From what I've read, recommended for "detailed mechanical workshops" or "normal drawing work", one step above "mechanical workshop" that I'm sure would have been fine as well
It does sound like quite a lot to me, but maybe reasonable for you. Your conversion from lumen to lux can. of course, be nothing more than approximate, since it depends upon the distribution of the light - and, in any event, your requirements in terms of lux are probably not uniform throughout the entire 30m². In both my garage and cellar (workshop), I would guess that there is less than 50% of the floor area which requires high level illumination.
Kind Regards, John