20-year-old Ashton has only had one outing in the first team and that only appearance was in Charlton's 1-0 over Carlisle in the Carling Cup.
The speedy left-back signed professional form with the Addicks back in 2005 and has represented England at U19 and U20 level. The Stratford-born players contract is out in the summer and he has come through the youth ranks at the Valley and has also featured in the reserves on a regular basis.