Another option for you is patterned concrete which is, theoretically, easy to maintain being weed free, etc.
Basically, they dig about 6/7 inches, put in the hardcore, then pour a bunch of dyed concrete, pattern it (number of options to look like cobbles, etc.) and laquer it. It can look fantastic.
I just got it done last week so don't know yet about the maintenance free,etc. but it does look great and will, hopefully, last for many many years being 6-odd inches of concrete. Eveybody who passes admires it. Wife picked the pattern which I wasn't just crazy about but she knows best.
This didn't help at all in your tarmac query but maybe you haven't considered the options available. Also, my only single useful piece of advice is be sure the contractor know you want to park cars on it (if you do). You do not want to end up with sinking.
Good luck.