Returning to Sheffield after your adventure is as simple as leaving :-)
The only thing you need to plan is your (pre-booked) return passage through Tinsley Flight.
The best strategy is to plan to arrive at Eastwood Lock the afternoon or evening before your return and moor at the visitor moorings overnight. You'll have around an hour the next morning to get to the bottom lock of Tinsley flight for your rendezvous with Dave or Derek who will again assist you up through the flight, leaving you at Tinsley Marina for your gentle cruise back into Victoria Quays.