It will *absolutely* be easier now than when he is 18 months. A 6-mos old is usually pretty easy to fly with, as they 1) aren't yet mobile so will stay in their seats, 2) sleep a lot, and 3) tend to adjust easily to other time zones.
But, every kid is different, so YMMV. I took both my kids to the other side of the globe multiple times in their first two years, and one handled it beautiful, the other less so.
Presuming LHR-AUH and AUH-MEL are EY apartments, I'd say it's not going to get any easier than that for the next, oh, 18 years
