Coach Eddie Jones will be without first-choice second-rowers George Kruis and Maro Itoje for the Autumn internationals due to injury and Lawes had been doubtful with a knee problem.
Prop Mako Vunipola is also ready to face the Springboks after recovering from a hip knock.
"Courtney Lawes has taken part in training as has Mako. We are in a good state of health and ready to continue our preparations ahead of Saturday's game," Gustard told the RFU website (www.englandrugby.com).
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Jones brought in Melbourne Storm defence coach Jason Ryles to work with the squad and Gustard praised the contribution of the former Australian rugby league international.
"Jason Ryles has been great, as a coach I need to get better and develop, as all coaches do, and it would be naive of me to think I have all the answers," he said.
"Melbourne Storm had the best defensive record in NRL last year, Jason is a young coach and has some ideas ingrained from playing in rugby league for 12 years around the contact and tackle area so we are trying to glean some information off him."
(Reporting by Ed Osmond; Editing by Ken Ferris)
