@Sam1989 - If you're on a training course, apply to join the trainees section of the forum, it has others that are studying and a wealth of information (and good knowledgeable mentors; Mine's a pint of bitter lads!).
You can also get help with some aspects of your learning BUT don't expect them to do your work for you, you'll at least need to have a good crack at it first and, where applicable, explain your reasoning.
Drop
@Dan @Lou or any of the site team a message with your course information and they'll sort you out.
I'm trying to add new material in there too when I can find good stuff.
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What's your reasoning for using 4mm throughout?