Hi everyone, I thought I would give an update on my situation.
i actually went to
London camera exchange to look at the 5d mk4 in person, and decided it wasnt for me as it looked a lot worse in person than on the photos, condition wise.
But actually holding a 5d mk4 was good as I was really impressed with the build quality of it, unfortunately the shop didnt have a lens that I could try it out with.
But I decided after that I wanted that model over the 6d, so a couple more weeks of hunting online and as of yesterday I am now a proud owner of a 5d mk4 in really nice condition with a shutter count od 23000.
I have also added to that the Canon 70-200mm f2.8 L IS mk2 and a 24-105 f4 L IS mk1.
I absolutely love it, not gone out with it properly yet but a few photos in my garden and I'm so impressed with it, absolutely worlds apart from my old set up!
Thanks for all your advice on the subject, its much appreciated.