Warm up:

200m freestyle
4 x 50m freestyle kick (with kickboard if available)
6 x 100m freestyle
6 x 50m choice of drill (e.g. long slow arms, fast kick - 10 kicks per 1 stroke)

Main set:
1 x 100m Easy - 20 sec rest
4 x 50m freestyle (2 x 0:50 second, 2 x 0:55 second)
1 x 100m Easy - 20 sec rest
4 x 400m Hard/Strong/Medium/Easy

Cool down:

Light stretches outside of the pool/in the shower, important to wind down after a long endurance session and recover the muscles.