In my experience nettles come back even when they've been glyphosated as their roots run easily and there's always a bit that comes back from somewhere. However, as Alina says it does become inert on contact with the soil and may be worth doing as a preparation to making your raised beds and dumping soil on topf of their remains. On the positive side, nettles are a sign of fertile soil that's fairly easy to work.
They are easy to pull up when spotted and do make great compost as well as a liquid feed if you can cope with the smell of them rotting in a bucket of water. As you are making veggie beds I assume you'll be out there regularly hoeing and tending and they'll be easy enough to keep cleared - easier than groundsel and bittercress and creeping buttercups and thistles and couch grass which are also a constant feature in my garden no matter how often I weed and hoe.
I too try to be as organic as possible and use no chemicals except for glyphosate every year on the paths between our veggie beds and the cobbled area at the front of the house. My garden is heaving with insects and birds and we have hedgehogs and voles and frogs and toads and newts too.
