Combining intervals, cardio and weights

[That Foreign Guy]

WTF, 6 foot 4 prop? How big is the other guy?

If you're a prop you NEED leg strength. Being a big fat bastard doesn't help. If you can't push you're not doing your number one job.

You have absolutely no excuse not to work legs (if the gym doesn't have any free weights what so ever, either quit or work them somewhere else. Ask a friend or random fat bastard to get on you piggyback and then do squats, get a bag full of sand and lift it off the ground, push a car round a car park, do something useful. Biceps don't mean [censored] in rugby until you're at a really high level (and given you seem to have no team training I feel safe in saying you're not).