Looking forward to his arrival Mills said: "Gary came in a couple of weeks ago and he has looked really sharp in training.
"I think most of the lads knew him already so he hasn't needed any time settling in and he has done well for us.
"I think Gary could add something a bit different to the side.
"We have got a few defensive midfielders at the club at the minute so bringing in an attacking midfielder could add a new dimension to the team.
"I know Gary is capable of good things."