The 29-year-old spent a week on trial at the City Ground, with a view to completing a loan switch, but the move was halted after the boss Steve McClaren’s resignation.
"I went up there for a week's training with a view to a loan deal at the end of it and I had a really good week there with a full 90 minutes under my belt against Stoke's reserves," Cook told skysports.com.
"I did reasonably well up there and was going back up on the Sunday night to be ready for training on Monday morning when I heard the news that he had left, so that kind of killed it for me.
"They told me that they weren't going to sign anyone until a new manager was appointed and then I could go back up for another week.
"It is just a case of waiting to see who is appointed and then hopefully get something done shortly after.
"It is a great club and, although I was only up there for a week, it ticks all the boxes, with a beautiful training ground and a big club with bold ambitions.
"It would be an ideal loan deal for me so that I can go up there and show them what I can do and then see what happens after that.
"I am eager to go out and play some games and I am confident that I can still play in the Championship at least, so I'm just waiting for the right move to come along and Nottingham Forest is definitely one that I'm interested in."
He added: "Well, due to the international break a lot of clubs have had a few days off and gone away on holiday, so it has slowed things down at Forest.
"They ideally wanted to get someone in before the next game, but they've had a large number of applicants, so it is one of those where I'll have to be patient for a few weeks.
"I know that the loan window is going to close in the first week of November or something close to then, so if anything crops up that interests me before then I'll have to look at that, but I'm just training hard at QPR and hoping something will happen soon at Forest."