You will often do long day’s ( 15 hour or 13 not uncommon ) sometimes unsociable hours so factor that in btw some pay £9.00 ph depends where you live & how many drivers there are looking
As Rog say often agency so no guarantee if you are in a job now you could register with a couple agency & work every other Saturday/Sunday that if you work a normal Monday - Friday job to see if you like it before packing in your job in & going full time
Might be better trying for your C+E as more options