Cambs to Midlands doesn't sound like you'll be doing much motorways - A14 at a guess.
Assume the journey home wil take up to twice as long as the outward.
Carry some drinks and eats. I f you are new to towing, then your biggest problem will be parking - motorways are good for this, as lorry and coach areas make it easy.
So, on the way out make a note of everywhere you could stop easily on the way back, bearing in mind the size of your combination, and the difficulty of manouevering. Some hints;
Many Little Chef's are suitable.
Supermarkets can be good, particularly if you go off to the far unoccupied end of the car park.
Even if you're not on the motorway, is there a service station at the junction where you cross the M1, for instance?
It takes a while to develop the "eye" you need to plan every move further ahead and to allow for the extra complications - eg to avoid reversing unnecessarily!