Szmodics and Lapslie available for selection.
Sammie missed the weekend win over Yeovil after taking a heavy blow to the face in the previous match against Crawley, whilst Tom has been absent since the victory over Bristol City.
Both have trained this week and will be in consideration for the big game against the Gills.
The U's are likely to be without Karleigh Osborne as he comes back from the injury that saw him miss the midweek match, with Bongani Khumalo set to continue alongside Tom Eastman in the heart of defence.
U's squad: Walker, Lewington, Briggs, Eastman, Wynter, Khumalo, Hewitt, Vincent-Young, Gilbey, Moncur, Fox, Szmodics, Lapslie, Lawrence, Massey, Sembie-Ferris, Murphy, Porter, Bonne, Marriott