AnthonyRees,

If your goal is to improve your rugby play, by getting bigger/stronger/faster, you need to drop that gym and invest in some kettlebells. That, combined with some standard, heavy implements like sandbags, rocks, poles, etc will be what you need. I played for 10 years, starting at the national level in college and ending with Superleague club play, and if I had known about kettlebells back then I would have been all over them. If you play in the backfield, you'll benefit from using them. If you play as a forward in the pack, you'll benefit from using them. Scrumhalf, flyhalf, it doesn't matter you can use them. Just the overall level of conditioning for your heart, back, ham-strings, glutes and quads will make you a better player, not to mention your upper body. I wish I had them when I was playing, We would have used them for conditioning if we knew about them. I believe there are even some articles on DragonDoor about kettlebells and rugby. Additionally, just look up "kettlebells for rugby" in Google and you'll find plenty.
Drop the gym, save your money and purchase some bells. Find a good RKC to show you how to use them and work hard. You'll be happy you did. Good luck!