I'm very supportive of anyone having a go at home grown, self sufficiency, off grid, all that sort of thing, however can I just share a bit of reality for a moment to put the project in to some context.
A reasonable barley crop might yield say 1.6t/Ha, given that the planned area is 6m2, expect a bountiful harvest of:
6*6/10000*1600=5.8kg
Ok, so that may be enough for a single batch if the malting process and other losses are kind.
It's been well over a decade since I turned a sod in anger so my agronomy numbers might be a bit rusty, but I believe this should get you in the ballpark.
I don't want to seem cynical, I'm really not, but I sense its worth scoping out the project some more, might avoid some later disappointment.
Anyway, agricultural seed & grain merchants, stock & station agents should sell you a sack of certified seed barley, there are defined varieties for malting grade, other varieties are used for fodder. Sowing rate is 20-50kg/Ha, while nutrition and growing conditions will impact on suitability for malting, simply sowing a malting variety doesn't necessarily mean that your crop will be malted, it's not a given outcome as there are many factors that impact on malting characteristics. In fact much barley that sown with malting grade in mind ends up as stockfeed, but if it does meet the criteria then it attracts a premium.
Hope this helps!
Some resources:
Seed:
https://eldersrural.com.au/farm-supplies/plant-genetics/
Agronomy:
https://grdc.com.au/Research-and-Development/GRDC-Update-Papers/2015/03/Barley-agronomy-and-varieties