On-loan Henry has not been given permission to play in the competition by parent club Reading.
Another wideman, Chris Hackett, sat out training this week with a back injury but he is expected to be fit.
Centre-half Darren Ward, who has been out since September with a knee injury, is close to a return but Monday night will probably come to soon.
Ashley Grimes is fit after illness but fellow striker Gary Alexander is still sidelined by a heel problem.
Andy Frampton, Scott Barron (both ankle), Zak Whitbread (hip), Pat O'Connor and Ali Fuseini (both knee) are still on the casualty list.