There are changes underway in Hatfield with a new Traffic Regulation Order being put in place by Herts CC to control the area in front of the station (the yellow lines have been painted) plus new dedicated short term bays within the car park itself. There will be a publicity campaign regarding the changes within the next few weeks, once everything is in place.
The new bays in the car park are there but it's hard to get anyone to go in. People fear they're charged on entry and don't see the bit about getting 20 minutes free.
There's secure bike parking going in too. Accessible via smart card.