Just in case you have missed it; the guidance from Defra & devolved governments is available to download (on their headed notepaper) from the BBKA website (under "Latest" on the yellow banner).
I have also printed off the e-mail I got from the NBU when I registered on BeeBase confirming that I am a registered beekeeper. Just in case the police aren't convinced by the bee stuff sitting in the car - but of course you have to be registered to have that