The Glasgow lock flew out yesterday with Andy Robinson's Scotland squad for their three-Test tour of Australasia, which begins a week on Tuesday against the world No.2-ranked Wallabies.
While Harley, who turns 25 tomorrow, has made the pool before, he has yet to be capped and is determined to make the breakthrough this summer.
The Warriors star said: "This is a massive chance for me. It doesn't matter whether I get my first cap against Australia or it comes against either Fiji or Samoa, it is making sure I get it.
"So that is going to make the next 10 days or so massive for me. I think what you did during the season may have helped you on to the plane for Australia, but it is what you do on the training pitches Down Under that will decide if you get a cap and how many you get.
"It is going to be very gruelling in terms of the heat and the hardness of the pitches. You are talking different conditions and obviously it is going to take a couple of days to acclimatise, but all my focus is on making the strongest impression I can in the build-up to the first Test.
"As I said, getting my debut against Australia is not the be-all or end-all but, if you can get in for the first Test and perform, then hopefully you give yourself the platform to stay in."
Harley's voracious appetite for the tackle could prove a big hit and the Warriors favourite is hungry to test his mettle against some of the most physical performers in world rugby.
He said: "The matches with Fiji and Samoa are going to be massive tests of our physicality. I think individually as rugby players they just love the contact so we will have to be ready for that.
"We know that we need to achieve positive results on this tour. During the Six Nations we started the tournament pretty well and should have beaten England in the opener, but that did not come and we were then under pressure pretty much from the start of the championship.
"So against the Aussies I think it is vital we focus on executing every part of our game plan to the max and let us see where that takes us. We know that there is talk of them resting their Super 15 players, but I think they have so much quality in depth over there that it is not going to matter who pulls on the gold shirt.
"So it is vital we front up against them. But I think the competition within our own squad to earn a starting jersey for the first Test will hopefully help us start that one in very good shape.
"This is a chance for this Scotland party to make a point for Scottish rugby and we are aware our pride is on the line."