Hey, this is getting quite exciting, military connection, wishing to keep movements secret, avoiding cities, lots of agents already undercover in the area. Are the accompanying children merely a front to avoid suspicion falling on you?
Anyway, my tip....check out that intelligence officer of yours, there is no e in Livingston, and the story about wakening at 05.00 to move your bike is most likely a load of mince. It is certainly not necessary if travelling to Inverness, but just might be if going to Fort William.
I suggest you make a decision as to visiting Livingston, do you want to visit it on the way north, or on the return journey south? If northbound, book sleeper London Euston to Edinburgh, visit Livingston then take a daytime train north to Inverness. On return, book sleeper berths from Inverness to London Euston.