Do you visit the US often/ever?
If so, and if this is an ongoing thing, I would open a checking account with Capital One (high street bank). There are no account fees and it has free ATM withdrawals and online banking. You can send a check to the processing centre by mail. Once it’s in your account, you can either just withdraw it via ATM (when all is said and done, with no fees and no commish and a decent rate, it’s OK) or if you have more time you can transfer it to your UK account using something like http://www.xe.com/trading.php or its many competitors.
Alternatively, you could open a USD-denominated account in the UK or in Jersey etc. Citibank used to do them but their shopfronts disappeared – don’t know if they still have a retail business like that. Avoid RBS International like the plague.