Leves are not good for combat no. Neither are FATEs really, although they were buffed so they're not terrible. Could probably do one char on FATEs before it gets too boring. Other than potd, it's just dungeons. Honestly DPS queues aren't that bad. While waiting, you can do beastmen daillies(not super great xp in HW but not bad), centurio hunt daillies(not that much xp but pretty quick if you use the website that show you where to go, get some centurio seals to unlock various things like mounts and pets too) and FATEs inbetween. And obviously roulettes but I'm sure you're doing these.
So yeah just dungeon runs, with whatever inbetween, can take a break and watch some TV shows or whatever, or can go crafting/gathering for a bit while queue pops, or can grind FATEs so it's faster although a lot more annoying, this kind of stuff.
Also make sure you have the preorder earring(iirc it's accessible already?), food and lvl 3 FC buff(via GC missions if your FC doesn't have it up, every week you can get 5 or 10 depending on rank that last for 2hours).