Hi Chris,
Decent second hand genuine wings do turn up here from time to time.
I bought a pair of genuine rear wings through The Samba and it didn't cost too much. If you want your car to be the best it can, then it's worth the extra time and money to hunt out the right parts. Patience is the name of the game!
I used Klassic Fab front wings on my car, also a '57 ragtop, and they're the best repro wings available. I bought mine through Evam Classics, but you might be able to source them through a UK supplier.
Best of luck.
Gavin