Thank you everyone, you've given me more useful information that I could've hoped for from this. I'm going to be incorpating every thing I can into what I already do and what I'll be starting.
Going to be working hard on the rucking and swimming (no fins) to begin, and then will move into tackling the finning beast once I can find a good place to do so (I dont think my local gym will allow to me to use fins in their pool) and someone to mentor me in the ways of doing so correctly and effectively. It seems everything I've read on here and researched about finning is that it is its own monster in itself and there are a lot of ways to do it incorrectly.
And now to finning.... relax your knees, use your quads, glutes and gut for the power use your gut and back for stabilization, but relax. think how a walrus or a flat fish undulates to get p0wer, and use the rhythm of both legs to propel you. Start on back finning, then switch to belly and then learn to roll right and left to switch.