How to print A4 double spread on a landscape A3

File>Print

Click the Spreads option - and type in 1-2 

Your setup is a bit strange

Best to have the backcover as the last page 

Or if you want it this way - it's best to have the cover in a separate file. 

But whatever suits. Just so strange to have the back cover and front cover at the start of the magazine.

Did your tutor show you that? 

Before we get into that, do you have a printer that can handle A3 sheets with a bleed? How are you going to print your drafts? That helps determine what we need to do to help you output your proofs.

You can just create a one-page A3 document and do your mockup on the larger sheet size. If it's just as prototype, page numbering doesn't even enter into it. So just design a document that would be a big as a two-page spread — or in your case, Back Cover/Front Cover spread — and print it out on an A3 sheet output device. You should get the perfect proof doing just that.

Hope this helps,

Randy