I admire your positive learning attitude and feel happy for your costumers who have such a thoughtful restaurant owner! Yes there would be tons of prep work ahead, as in terms of food safety, its pretty serious!!! But instead, you might widen up a whole brand-new selling point of your restaurant and all gluten free customers will depend on you and appreciate all your hard! (like my gluten free friends! They would only go for specific places to eat! )Then they will spread the words and bring you more business! You have no idea how much these gluten free customers are desperate to find a proper gluten free diner/catering!
When doing the prep, just bear in mind that, check the ingredients table from ALL condiments/sauces (you will always be surprised whats in there! ), ask yourself if all groceries been exposed in a gluten environment (if any normal flour bags leak, break, etc, or using the same cloth/tea towels which just been used on gluten-traced food/ stuff) use separate tools utensils and equipment like you are running two separate restaurants.Once you get your hand on it, you and the chef will get used to it like your second nature and feel no need to moan at all
Again, its a good thing to truly care about your costumers and wish you all the best !!!
BTW you could have starter trial first, like providing gluten free menu only at specific days/time, my gluten free friends remember which fish-chips place offers gluten free on Monday or before what time (as the first oil pot)