As you´ve just started, I´d not exactly recommend jumping to mods, because, as a tendency, mods are harder than the vanilla game.
If you want a different scenario and don´t mind somewhat dated graphics, try and get a decent copy of MTW (try to avoid the one that has een warned about here in the forum, there should be a sort of Bargain Bin version of MTW+VI about, I believe that´s what I´ve got, and that´s about all you can ask for. Try ebay or something if need be). It plays decidedly different from RTW (in my opinion it´s harder, and I think I´m not the only one to think that). Finally, you could also try another faction in RTW, they play very different to each other. If you don´t have a Roman campaign finished you´ll have to unlock the other playable factions first, but that info is in the guide of the Frog Goddess
In the end, the choice is yours.