I'd suggest a smoked Gouda or a Havarti to round out the cheeses.
By itself ratatouille isn't enough for a main course. Maybe a Mexican rice and bean dish, or a hearty cheese bread as a more filling accompaniment.
I love ratatouille. I use onion, garlic, tomatoes, zucchini, eggplant and either green or red pepper, with olive oil, basil, thyme, oregano and fresh parsely, salt and pepper.
I like the vegetables in fairly big, but bite sized chunks, stewed well until tender.
For the tomatoes - either use canned diced or whole tomatoes (with the whole ones just pick them up and squeeze them as you add them to the pot), or peel them beforehand. To peel tomatoes, boil a pot of water, toss in the tomatoes and lift out with a slotted spoon when the skin starts to split. Cool, and the skins will peel of easily by hand. If you can't get good fresh tomatoes, use canned rather than unripe fresh ones.
For the eggplant - I like to use the long, skinny Asian eggplants. It helps if you cut up the eggplant, salt it, and let it sit for about an hour, and then rinse thoroughly. This makes it less bitter, and gets rid of some of the excess water.
Smaller zucchini tastes better than larger.
Saute the onions first, then add the zucchini, then the garlic, then the green peppers, as sauteeing green peppers too long makes them better. Then add the salted/rinsed eggplant for a minute or two and add in the tomatoes and juice and herbs. Simmer until the veggies are tender, and add the salt at the end to correct the seasonings.
It can be served warm or at room temperature, and is actually one of those dishes that tastes better the second day, so you can make it in advance.