I usually take this as a handy A1 session, of course a bit of intensity can be added to get more of a work out. This can be adapted for all four strokes by substituting the one armed fly with another drill.
150m Fc, 150m Bc, 100m pull, 100m kick, 100m swim
6x200m broken down as follows: 50m kick, 50m drill 1, 50m drill 2, 50m full fly. 15-20 seconds between each set.
8x25m fly sprint with 20-30 seconds rest, focusing on pure speed, the rest should allow adequate recovery.
200m Bc recovery
Drill options: one armed fly, broken fly, bondi drill, fc kick with fly arms