As Baldy said, Ocala is good for trails. Additionally you may head to Gainesville just north of Ocala. We have the San Felasco trail, which has about 30 miles of bike trails. There are also numerous rail trails in the area. As mentioned, gravel doesn’t really exist in FL, it is a lot of sand and sandy soil, with a fair amount of roots to watch out for. Central Florida at least has some “hills”, with some of that formed by old sinkholes. Feb-Mar is a good time, weather is usually still pleasant and humidity isn’t kicking in yet. As a note - despite the amount of rain we get, I use a dry lube on the chain and just make sure it is cleaned and lubed. You will pick up a ton of sand with the wet lube.