Pannier/ Cycle Bag/ Bike Bag / Bicycle Bag (Streatham Hill SW2)

Hello! I’m looking for a pannier/bike bag that can be attached securely to a rear bike rack. Will be used for groceries, and should ideally be able to hold a decent weight securely.

I volunteer regularly to collect surplus food from designated local grocery stores and then distribute it to designated charities and individuals in the community. Donations often exceed what I can fit in my backpack, and a pannier will help me transport more, more safely.

Any style, any colour is fine. I’m happy to make minor repairs. Waterproof preferable but not essential- collections and distributions happen rain or shine!

Thank you.