Henderson said: "Putting in full contact training was important to me. There was no point in being apprehensive about it, I decided that I would have to smack into someone and see what happened.
"I hope to be playing as soon as possible. I have been to Ireland already to put in some fitness work and they told me I had to get some matches under my belt before I could be considered.
"I played in the last Test against South Africa and am very keen to be in the next one against Italy.
"Swansea would be a good opportunity for me and, as I have played against them a few times, I would like another crack."
Greening is being more closely monitored because of the knee injury which gave him problems during England's autumn Test series. But he has played in 17 of England's last 18 Tests and fears that he might miss the Six Nations are receding.
Wasps' director Nigel Melville said: "Other players like Peter Scrivener in the back row are regaining fitness which is very encouraging.
"We cannot make any progress in Europe in our last two pool games against Swansea and L'Aquila, but we are back to league matches straight away and will be building for them."
Gloucester have terminated the contracts of winger Rob Jewell and lock Richard Ward by mutual consent.
Jewell, 22, has made six appearances this season, but 30-year-old Ward has not featured at all.
