The former Desperate Housewives hunk popped the question to Cara in August (16) after a decade of dating, and now they know they are spending the rest of their lives together, the bride-to-be confesses she is taking a more relaxed approach to wedding planning.

"We're going to get married in September, 2018, so I'm going to start planning this time next year," she tells

However, the couple has a good idea of how they wants their big day to play out.

"Small, intimate, 80 people, Martha's Vineyard (island in Massachusetts) - call it a day," Cara, 32, reveals, admitting she will be "very particular" when it comes to food and accommodation details.

She adds, "I want to make sure my guests enjoy, but anything else I'm like, whatever."

Metcalfe, 37, will also be heavily involved in the planning process, but for now, they are happy to just enjoy being engaged.

"I think there's a sense of calm," Cara continues of life as husband and wife-to-be. "There's a sense of unspoken security that when you're not engaged maybe there's like an underlying uncertainty.

"Now that we're engaged I feel this total sense of calmness. Like, we'll get to the wedding. We've got the rest of our lives."