Same here. I applied priority as well, and enrolled biometric on 11 April. Supporting documents received in Sheffield on 17 April (tracked postal service). We received our documents back on 2 May, but only got email from UKVI on 3 May, acknowledging receipt and that application will be forwarded to ...

Agree with what 4uvak said, just send the documents with explanation. And I hope this will make you less nervous... During biometric enrollment, when I handled in my passport to VFS, they actually scanned my passport and all pages with visa/travel data in it after they scanned my printed application ...