The 2005 Lion could have been added to Saracens Heineken Cup squad ahead of their clash with Racing Metro 92. But the Vicarage Road club have chose not to register the 28-year-old and he is set to make his debut in a Boxing Day clash against Wasps at Wembley.
"I just can't wait to play now," said Henson."I'm just trying to impress as much as I can in training with Saracens.
"The way I look at it, Saracens have used me for promotion for the Boxing Day game so they are going to have to play me now, I'm hoping.
"It would be a hell of a game to come back to. I'd love to be involved in that one. They've got a couple of injuries so I'm hoping I'll force my way in."
And although Henson only signed a contract until the end of the season both parties hope to secure a longer-term deal.
"The intention on both sides is to put something together long-term in terms of a contract, which we would aim to sort out before the end of the season," said Saracens Chief Executive Edward Griffiths.
"Hopefully Gavin will be involved with Wales in the Six Nations and then we would try to conclude this around April.
"He is training with us on a regular basis and each time a session finishes the coaches are talking about the special things he is able to do on the pitch."