Awwww thats a bugga Ang!
Almost the same thing happened to me, I failed on 46kph
I did the DAS on a 500cc bike, rode it all over for 3 days and like you, had to ride about 15 miles to the test centre.. through rush hour traffic and passed a big RTA, and then had to ride it back to the school!........but because I couldn't go through a stupid speed trap 4kph faster than I did, I failed.
Kissed goodbye to £650 just like that!! and now cant afford to do it again Grrrrrrrrr Oh.. and I had a bloody nail in the back tyre which the instructor sheared off and covered in leaf mould/mud just before the test! ...sorry rant over.. keep your chin up, you will do it next time
xxxx