Warburton's last competitive match was for Wales in their Grand Slam decider against France in Cardiff on March 17, but a nerve problem in his shoulder meant that he only played until half-time.
"I'd been playing straight through from August, when the summer Tests started, right through to the Six Nations and my body was crying out for a bit of a rest.
"As much as I wanted to play for the Blues, I had to take a break to get the shoulder right. Now I've had a bit of a rest my body is crying out to play again - I'm getting withdrawal symptoms, so the sooner I get back the better.
"Training has gone well, I haven't felt off the pace and I've gained some good weight. Of course, I would rather have gone into an international match with a few games preparation under my belt, but I'm very happy going into the first Test this weekend."