"I never want to eat sandwiches."
Translation:Je ne veux jamais manger de sandwichs.
There's no direct correlation between French and English in terms of when when you use "à + infinitive" and when to use only the infinitive. With things like "Je veux/voudrais manger", "Il faut manger", "On va manger" etc., where you have a verb immediately preceding, you don't need "à" before the infinitive. There's probably a better rule of thumb & way of explaining, but that's how I think of it