BA should fund your essentials. During hurricane sandy I was without my bag for 4 days my essentials came out as about £30 worth of clothes and toiletries, that was in danger of jumping considerably (nearly doubling) if it had been much longer, as I'd have had to buy a new pair of jeans.
I believe some people in mcdonalds like jobs have to wear uniforms, or "suits", and claim these can cost hundreds of pounds and it's absolutely essential. That's between you and BA to persuade them
