They will both contain gluten. The amount of potential gluten is indicated by the % protein (gliadin and glutenin) on the product nutritional information table on the packaging. AP (plain) and SR is usually at or around 10%, while strong bread flour is between 10% and 13%.
Self raising flour is nothing more than a shortcut. It is just plain flour with baking powder (and maybe salt depending on location and brand) added. Baking powder is a leavening agent that gives rise to the dough, either single or dual acting, and if used, bread made this way should not require yeast. Plain flour can be given rise by adding your own baking powder at about 3% from memory, or yeast. It should be unnecessary to use both but some recipes do.
I don't rate naan recipes that use self raising flour with additional baking powder as it is not needed and I can taste BP overload every time. Some people are less sensitive to the taste of excess baking powder. I'm not one.
Baking powder is usually bicarbonate of soda (Sodium bicarbonate) mixed with cream of tartar (tartaric acid) for chemical rise (single acting or home made) and other salts for heat induced rise (double acting). This can be a salt of aluminium or other.
There are no hard and fast rules for naan regarding which flour to use. Atta, Maida, plain, all purpose, strong bread, or SR baking powder, fresh or instant yeast, egg or not, yogurt, milk, water, butter milk, etc. It is a matter of personal preference. Find a recipe you like and use it. I have my go to naan recipe now, finally. Actually two. The SAF naan is very tasty and the full dairy deluxe naan is rich in flavour and texture.
https://www.196flavors.com/india-naan