Woo, you have booked yourself on to a Twin Made workshop and you may need to get fabric. Here are some places to take a look:
For Fabric Shops: Try Cardiff Market, Hobby Craft, The Pumping Station or IKEA. Sometimes Recreate Scrap Store has suitable fabric in stock
On-line:
Ikea have a Re-Shop and Re-Use section on their website which sometimes has suitable fabric.
Fabric Land https://www.fabricland.co.uk/
https://brunswickmills.co.uk - Run + Fly Supplier
Minerva https://www.minerva.com/ - check postage time
https://www.fabricgiant.com - Printed Cord
https://fabrikate1.co.uk - Local Seller
I try and use as much unwanted fabric as possible. Turning tea Towels into shirts and leftover cord into jackets!
After each Twin made workshop you will keep hold of your pattern and have a guide so you can make lots more.