Hi @marcusbarnet,
this is a very difficult question to answer.
From your question, it is not clear, that if you are aware of some facts about designing x86 boards - especially, that they are expensive to develop. Maybe have a look at these my blog posts, they can help you understand background of designing complex boards:
1) How much a custom x86 Motherboard Design / Development cost
Page not found. You have landed in the wrong place. You will not find FEDEVEL educational courses on this page.
2) x86 Custom Board Design – How long it takes?
Page not found. You have landed in the wrong place. You will not find FEDEVEL educational courses on this page.
Also, designing x86 board is quite complicated. Of course, it is possible, but it would be great if you have had some processor board design experience before. I know, that in your email you mentioned that "I’m a mechatronics engineer and I only designed boards based on ATMEGA micro-controllers." .. so ... yes, courses will help you to learn and understand something new, but .... there are no miracles.
I wish it was so simple to learn to design complex board as watching a video, unfortunately, it's not. I am sure you understand what I mean.
"I read that the course is based on a iMX6 ARM processor: is there any difference between the AMD x86 architecture and the NXP?"
- ARM and x86 boards are very different. Especially power management is much more complicated in x86 ... + do not forget BIOS in x86
"Does it cover topics like how to make connections between CPU and video output, RAM and memory?"
- Advanced PCB Layout covers DDR3 layout, HDMI, LVDS, ... etc
I hope this helps.