Welcome to the Mortal Realms! For a 1K army, I'd first recommend being Thunder Lizard for your subfaction as the Stegadon will be batteline already. The Carnosaur could be an Oldblood or Scar-Veteran for your general, and you'd have 445 to work with.
For the other battleline, you could go fast cavalry with some new Aggrodon Lancers, and a unit of Saurus Warriors. You won't have the magical powers, but you'll be pretty fast with some good 'teeth'.
Then to increase up to 2K eventually I'd look to get a Bastiladon and a Slann Starmaster, plus more Warriors or some Skinks, and then another support hero or two. Seraphon are in a great spot now in terms of models and rules. Many ways to play, many tools in the box. I look forward to fighting them again in the new tome, and losing horribly again as I always do to them, seeing how many heroes (if any) I can assassinate with my Clan Eshin