Mick.....I would head straight for the I4 East which ends/merges with the I95 at Daytona Beach. Should take around 1.5 hours.
We have done this journey several times in reverse when we stayed at Daytona one year. We have also travelled from Kissimmee to St. Augustine on several occasions (a nice, relaxing day away from the theme parks)....that is about 45 minutes beyond Daytona, north on the I95.
Alex