Cheers Matt, depending on how quickly you recover from a session so you are still good to go on Saturday for your game will be the big determinant, whether you do a solid repeated speed session, or a indoor rowing session, or a swim interval session, so there are a plethora of options available to you:
repeated speed
10 x 40 seconds run with 20 second walk recovery
10 x 30/30
10 x 20/40
ideally with distances set off of a 2,400 metre time trial, or if not try and work on a rugby field and do the following:
10 x up and back on the field (200 metres) – 40/20
10 x one length plus 50m – 30/30
10 x 1 length – 20/40
you can do the same times and recoveries on an indoor rowing machine
or you could do a fartlek cross country with a 30/60/90 seconds blast at high intensity every 3 minutes of running, do this for 45 minutes
swim intervals
10 x 25 metres in as few breaths as possible work 1:1
10 x 50 metres as above 1:1
10 x 100 m as above 1:0.5
good luck and go for it, ash