Thanks one and all!
Some really useful info here that will better preprare me for the journey ahead.
I have made some changes to the original plan. I am now on the 1045 crossing from Dover and so will be leaving Manchester at the (un)saintly hour of 4am - Nice!
I am hoping that this pushes the window just a little bit in my favour regarding the traffic round London. Fingers crossed!
Cheers
Jason