The 22 year old current U21 international played for a City reserve team at Wycombe on Wednesday afternoon.
The Bluebirds won 2 - 1 with goals from Joe Jacobsen and Jon Kift.
"Lee is not attached to a club right now and is spending some time with us," said reserve team boss Paul Wilkinson.
City currently have two senior keepers in Neil Alexander and Martyn Margetson. The third, Tony Warner, is currently with Fulham on loan.