Only going by what you said,
"On my PC the main/PC display is always the mini hdmi port with my television no matter what you set as the Main display." < TV is Main display.
"When I hit win+P and select secondary only it should leave me with just the TV running but in Fact the opposite occurs. " < You selected secondary only, which is the other display, not the TV.
Your definition of main display and mine must be different. In Windows you can set what ever monitor you want as the "Main Display". This has nothing to do with what screen shows the POST and the Windows Boot Screen, that will not change. What will change is what happens when you press the + P keys. If you select PC only, only the monitor set as the Main Display will stay active, all the others will go blank. Change which monitor is set to Main Display and it changes which monitor stays on and which goes off.
In the Customize Display Screen like shown in post number 6. Click and drag the big box 1 to the other side of 2 and let it go. Then click on Identify. It will show which identity your TV is assigned to and which identity your Monitor is assigned to. Click on the big square that is the same as the identity your monitor is assigned to, when that is highlighted make sure "Make this my main display is checked." Click apply if you have to.
Humor me will you and try this. Go to Settings > System > Display. You should see your monitor layout and the screen numbers. Click the one that is not the TV so its selected. Now look down at the bottom and see if the "Make this my main display" is greyed out. If its not, check mark the box and click apply. Now press + P and select PC only. It should be the only screen active now. Select secondary only and your TV should be the only one active. If that's what you want leave it that way. Now select Extend and they should both be on. If that's not what you want select the TV and put a checkmark in the box for Make this my main display. Now PC only will be the TV and secondary only will be the other screen.
This will not change which screen shows the BIOS Boot screen or the Windows Boot screen or logon screen. Just because that shows on the other monitor doesn't mean your main display changed on the reboot. Once you log in it will be the way you last left it. Mine always shows on the monitor number 2 in the screen shoot I posted earlier. The one numbered 1 is set as my main screen.
My screens function perfectly as I stated in my first post, its the fact that my television is always identified as #1 despite being the secondary screen. Did you read the link I posted?
I'm assuming on Nvidia cards that the HDMI is always (0) as you refer to it as my tv has been labelled #1 since very first time I started using dual monitors years back.
If this the case I could solve the problem using a HDMI/DVI adaptor but then I'd lose the sound signal to my tv which is a no go.