Yesterday I was forced into a situation where I had to pay a UK Invoice in Sterling using PayPal and I only have my Greek Euro credit card registered with them. I got 4.5 % worse than the fixing rate. It makes the poxy airport rates suddenly look quite attractive.
I can't help you with cash, Allan, but if you have a relative or friend that you trust, who you will be visiting early in your trip, I could transfer Sterling to their account and you could transfer Euro to mine here. Exchange at whatever the fixing rate is when we make the transfer. Filippos' offer would give you enough to get you to their house.