Cook the zucchini.
Heat a large skillet or large sauté pan over medium heat, add oil and heat through. Add the zucchini, working in batches if needed. Sauté, until the zucchini is tender, about 4 minutes
Cook the pasta.
Bring a large pot of salted water to a boil. Add the fettuccine and cook, stirring occasionally, until al dente, about 6 to 8 min. Reserve ½ cup of the pasta cooking water then drain the noodles and return them to the pot.
Toss with the lemon.
Add the butter and squeeze the lemons over the pasta, adding the squeezed lemon halves to the pot and tossing to combine until the butter has melted.
Add the zucchini.
Add the zucchini to the pasta and toss once more, adding about ¼ cup of the pasta cooking water if needed.
Assemble and serve.
Top with the feta and dill and toss once more before serving. Portion into warmed serving bowls and serve immediately.