Liddle has been out since suffering ankle ligament damage during the 1-1 home draw against Bristol City in December when he was injured in a challenge with Robins player Greg Cunningham.
The 27-year-old recently stepped up his rehabilitation and is eager to make his comeback and help the Magpies in their battle against relegation from Sky Bet League One.
He told the club's official website: "It's coming on slowly but surely and I'm feeling good, as there's no pain around the ankle any more.
"It's just a case of getting back into things now but the physios say I'm still a good few weeks off.
"Hopefully I can build my fitness up and start getting on the training field again, because it's been two-and-a-half months of pure frustration for me.
"I don't know how many games I'll get to play before the season's out but I want to be involved in as many as possible.
"I'm not going to rush it for the sake of risking my career but it's just a case of building my fitness to persuade the physios to let me get out there sooner rather than later."