when i passed all my flight tests and had to send of for my little blue book, i drove down to gatwick and gave them everything by hand.
just make sure you have a copy of the last few pages of your log book and copies of everything else they ask for. i infact have a second logbook not because im scared of a fire or flood washing it away, but because i dont trust royal mail.
only downside is that the CAA send everything back in the mail second class (i think). deffo not recorded though although if i remember right, they do give you the option to go down there to pick it back up.