And I fixed it!!
After @engikeneer confirmed that it should work with no need to have the extra lines in the start g-code and @Arnold_R_Clark advising me to do a re-install and that didnt work it got me thinking, so i just did a system rollback in win10 to before i even downloaded PrusaSlicer.
I then went and checked in my appdata folders and i found a very old installation of PrusaSlicer from over 2 years ago, i must have tried it uninstalled and forgot, i used to run simplify3d before installing ideamaker.
deleted the old appdata files, ran a regedit scan using CC cleaner and that cleared out a pile of old broken registry files relating to PrusaSlicer and a reboot and re-install and it now works as @engikeneer said it should. it must have been windows being windows..
thanks to you both for helping me to fix this with the confirmation and the re-install ideas. i will mark it as a question and solved.
thank you again