To be honest the best way to deal with it is just to do it, i was petrified of motorways so much so just after i passed my test i drove up all the A rodas to Manchester and it took hours and hours, so on the way back i ended up driving on the motorway absolutely pooping myself! it took me a good 7 years to get used to driving on the motorway, i would grip the wheel so hard my knuckles would be white!
Ive always had a bad fear of breaking down on the motorway, anyway not so long back i was driving up to manchester and we were stop start, stop start all the way through Trafford parkd, anyway i ended up in the middle lane sandwhiched by huge wagons and had come to s standstill, traffic started moving and my car would not budge, i absolutely shit myself, anyway a wagon driver helped me to get my car to the side and we waited recovery.
To cut a long story short recover came took us to the nearest centre, i tried my car again and it worked, so i drove it to where i was going and drove it back down the motorway shitting myself incase it happened again, it was fine.
Anyway, we have been here there and everywhere, Sullfolk, Wales, Scotland and i wouldnt stop driving on the motorways now.
So if i were you i would just do it xxx