​Facebook closed groups for fabric and zips, all of whom I have ordered from successfully. You have to request to join them:

• Crackers fabric - https://www.facebook.com/groups/CrackersFabrics
• Bag Kits & Glitzy Bits - an offshoot of Crackers Fabric https://www.facebook.com/groups/BagKitsandGlitzyBitz 
• Tania Fabric - pre-orders for cork and quilting fabric plus zips and pulls https://www.facebook.com/groups/TaniaFabrics​ also has a website but not as much on there and pre-orders are done through FB https://www.taniafabric.com
• Bags of Difference - Bonkers Bags and bling hardware also has a webpage with some items to order​https://www.facebook.com/groups/BagsofDifferenceBaghardware/?multi_permalinks=828740551057648&notif_id=1618336297049470&notif_t=group_highlights&ref=notif

 
Zipper Station for zips also on eBay. We used a No 3 zip but a No 5 would also work; they tend to be used on bigger bags as they are stronger - https://www.zipperstation.co.uk 
 
Bag makers groups which are closed groups also to join: 

• Amy Lynne group - https://www.facebook.com/groups/patternsbyamylynne 
• Leanne Mosely https://www.facebook.com/groups/craftedbyleannepatternsgroup 
• Spencer Ogg https://www.facebook.com/groups/spencerogg

They all have business Facebook pages, but these are for their fans and have freebies, which can be downloaded from within the files sections.
 
YouTube videos

• Amy Lynne Butler Method https://www.youtube.com/watch?v=RFQ9xdHmTYY
• Amy Lynne easy peasy pouch https://www.youtube.com/watch?v=wfwNBQj8vV0