I'm going to be using it mainly for photo editing aperture and lightroom and maybe some video editing going to be doing a bit of gaming but mainly Football manager. I was wondering am I better off upgrading for fusion drive or i7 and will I be ok with the 675 GPU
If you're planning on simple video editing, which seems the case, don't worry about the CPU.
Same if you're games are Footbal manager and the likes.
Top CPUs and top GPU are only needed for very heavy -professional- video editing and latest-greatest games like shooters and the like.
With the fusion you'll notice a clear, impressive difference in overall system speed in any task you need, i totally recommend it. My slow-CPU MacBook Air feels way snappier than my old MacPro in regular usage, and that's just because the OS and Apps are on SSD.
If you still have money, then go for the GPU, it will let you play big games (it counts a lot more than the CPU in games) and increase reselling value over time in case the people you want to sell is into gaming.
CPU is important on very few specific tasks, 99% of users and apps don't even use it at half of its potential.