It would be a little smoother to say "Yesterday,I decided to drive to the city, which in my case means two hours' driving" or "Yesterday,I decided to drive to the city, which in my case means a two-hour drive"

It's okay, but you need a comma, after the word "city".

"Yesterday I decided to drive to the city, which in my case means 2 hours driving." or "Yesterday I decided to drive to the city, which in my case is a 2 hour drive."

Yesterday, I decided to drive to the city, which in my case means a two hour driving. you can use a 2 or two ether will be understood