Hi KBee,
I've not used the Post Office service, however that's because the simplicity of using PayPal to transfer money for free is so good. Perhaps the exchange rate itself isn't as good as the post office, but I'm hazarding a guess that the fee's even if just a few pounds would then make the actual amount received/transferred pretty much the same or, still making the PayPal route better. Will keep a lookout for the Post Office route and evaluate soon!
Cheers, DtM! West London & Slough UK!