IT DID !!!!!, soon as I got home! -- took the car out for a run, purely to re-charge the battery, blow the cobwebs out etc. Couldn't wait, feel so isolated without a car. I knew I could drive, I had moved the car around the driveway to make space for my neighbours car a couple of weeks ago.
When I discussed driving with my surgeon before the op, he said he would be happy with 4 weeks post op if the physio was satisfied with my progress,
didn't see physio week 4 so had to wait until week 5
Trips will have to be interspersed with breaks every 1/2 hour or so, just to stretch my leg. 90% of my trips are less than 1/2 hour so all is good. Hope to go to our daughters in 4 weeks, that is 3 hours drive, so planning cafe breaks.
This was a real milestone in my recovery, cheered me up no end. 
Next milestone, get knee to bend far enough to use exercise bike. Watch this space.