Am I entitled to pay for driving my company van home

As a general rule, you are not paid for driving from work--including from your last job site--home, or for driving from home to work--including to the first job site. Under the law, that is considered your regular commute to/from work (there being no difference between driving from home to the office to start the work day, versus driving from home to the 1st job site; same thing about the trip home at the end of the day), and there is no obligation to pay you, though your company is free to be more generous and voluntarily pay you for one or both of those trips: your empoyer, if they are paying you for the morning drive, appear to be paying you more than they are required to. If your employer chooses to pay you for traveling one way, that does not require them to pay you for the other.
Again, this is the general rule. There are exceptions: if the trip home from a job site is *much* further than home from the office, you should be paid for the extra time/distance, which exceeds what the commute from work would be. E.g. if traveling home from the office would be typically take 30 minutes, but home from the job site would  typically be 60 minutes because it's twice as far, technically, you should be paid for the extra 30 minutes. But if the difference in time is fairly small, that will not be enforced both because the law does not worry about "de minimis" (or minimal) extra work time and also because given the vagaries of traffic and travel, a small amount of extra time one day could be getting home faster instead the next; it's too random to base policy on. Besides which, the only way to force the employer to pay you any additional travel time is to take legal action against them, which is a drastic step and one that should not be taken lightly.