While Henson has been widely backed as a potential midfield partner for Lions skipper Brian O'Driscoll against the All Blacks, he expects fierce competition.
England World Cup winner Will Greenwood, the precociously-talented Leicester centre Ollie Smith, Ireland's Gordon D'Arcy or Henson's Wales Grand Slam colleague Tom Shanklin are among options available to Lions boss Sir Clive Woodward.
And the presence of such quality is not lost on Henson, a key figure in Wales' irresistible charge towards Six Nations title glory this season.
"It is going to be difficult to get into the Test team - there are a lot of centres going," he said.
"People say the easiest thing is being picked (for the squad), but now it is about getting a Test place.
"With Brian O'Driscoll as captain, there is only one centre spot up for grabs, which makes it even more difficult."
Given his versatility, Henson could conceivably feature as a fly-half or full-back by the time Woodward announces the team to tackle New Zealand in Christchurch on June 25.
Either way, Welsh rugby's newest superstar is chomping at the bit to challenge himself amid an unforgiving environment of Lions rugby in New Zealand.
"It has been a pretty special season already, winning the Grand Slam and Celtic League title. I didn't think it could get any better, but it seems to be getting better all the time," he added.
"It hasn't really sunk in yet. It is a great squad of players, and it will be superb to be around those players and watch how they train.
"And with the coaching party that is in place as well, hopefully, I will learn loads and improve as a player.
"It is unbelievable, really. Two of my mates sent me text messages to say I was in, but I didn't know whether to believe them or not, and then my mother rang
and she was crying on the phone.
"I was disappointed when I didn't make Wales' 2003 World Cup squad, and I expected to get in that, so I wasn't really expecting too much," said Henson, who was at Shannon Airport following the Neath-Swansea Ospreys' Celtic League game against Connacht when news filtered through.