Henson toured New Zealand with the Lions six years ago and made four appearances.
"I'm starting at 12 this weekend against Stade Francais," said Henson.
"I'm so happy to be back playing now. I think it's been probably about two years since I started at 12."
"I'm a little bit nervous, going to be excited as well. Can't wait for the game."
After coming out of his long-term self imposed exile Henson made just four appearances for Saracens before he signed a five-month deal with Toulon.
Henson is only eligible for four of Toulon's remaining regular-season games and admits he is playing for his future for both club and country. But he still holds on to his World Cup dream.
"I'm on trial a little bit, but I'm not going to put pressure on myself," said 31-times-capped Henson.
"I signed for them, but I had to play five or six games to get a two-year contract in place.
"But that is out of the window because I didn't realise my calf injury was as bad as it was.
"I'm hoping once I play they like what they see and hopefully the contract will be in place.
"My aim is to play four games and if we do get in the play-offs there will be four games again. I absolutely love it down here. I'm so lucky.
"If I manage to start the four games for Toulon I'd like to think that Wales would at least try me out in one of those summer games.
"I'm aware there are summer internationals with Wales and a World Cup round the corner. I still think I have got a chance for the World Cup.
"It's been a bit of a nightmare getting that calf muscle with Saracens, but maybe it was a bit of blessing because this opportunity came up.
"I only started about 10 days ago so I have had about two months without running which has not been ideal.
"But to be fair I've got some confidence from training. I'm looking pretty sharp and the skills are all there. I've got a lot of quality players around me and I'm back at my favourite position at 12. So I'm really excited about playing again."