Butland, who is currently in Qatar receiving personal rehabilitation, has been out for a year after breaking his ankle while playing for England.
Lee Grant has deputised well in his absence but Butland will be hoping to win his place back before the end of the campaign.
Mellor admits that Butland has endured a tough time on the sidelines after a number of setbacks but feels his client is in a positive place as he targets a return in April.
"He's feeling absolutely great now because he can see clear light at the end of the tunnel," Mellor said.
"He was in the office last week before going to Qatar and was in fantastic spirits.
"By the time he gets back to playing it will have been 12 months, which should have been three months, so there's been some really down periods for him. But he's in a great place now and ready to go.
"He hopes to be back on the grass playing competitive games for the under-23s before the end of March, hopefully mid to late-March.
"Then hopefully he will be challenging Lee Grant for the last six or seven games of the season."