beside drawing my hobby is medieval costumes - maybe when I get access to my books again (everything still in moving boxes) I can give you some tips. You just have to say how in depth you want to go (and I´m talking about discussing kind of weaves and stitchlengthes ).
A good begin for fashion and armour from 1300 - 1450 is this Eduard Wagner
It´s quite cheap - if you go into costuming you can easily spend a fortune (look at my credits )
PM me after christmas and I will see what I can work out for you
<Insert witty remark here>