Honestly, the guys on the Bladeforum Knife Makers section would be able to better answer your question and give you general knife making advice:bladeforums
I've done a good bit of welding in the past but never any forging. I always just used an open back leather bib with full length sleeves, but I could definitely see how you would want a nice thick leather apron when standing in front of a forge for any length of time.
I'm honestly surprised they don't have one available to use for the duration of the class or can't point you to a place to acquire one. Cheap split-leather welding aprons cost in the neighborhood of 40-50USD, while a nice heavy-duty horse hide, full-length apron could run into the hundreds of dollars.
30 second interwebs search turned up a cheap and a more costly optionCheapExpensive
One problem you might run into is that some of the smaller shops may not ship to your country or that it will be prohibitevly expensive when you add shipping and VAT in.