"MMA" is not a fighting style, it's a mixture of different martial arts combined in one.
Many gyms advertise MMA training to pull people in there, but what you will find out is that majority of gyms seperate the stand up (boxing/kb/muay thai) and ground work (wrestling/nogi grappling/gi brazilian jiujitsu).
Expecting to walk into any martial arts studio as a newbie (person who hasn't trained martial arts in anything) then jumping into an "MMA" class is unrealistic.
Dynamic MMA:
www.dynamicmma.com
1 free week, unlimited training for kickboxing and the bjj classes. There are MMA specific classes but are only for the amateur and pro fighters in the gym. You can also get in the classes if the instructors feel like you can hang.
You will not learn very much in 1 summer (2-3 months). You will get your bearings and that's about it. Especially if you're looking to learn grappling.
It will also depend on your athletic abilities, and your agility/mobility, and your ability to learn to move. Learning to throw a punch or kick is more than just cocking your fist back and throwing it forward.
Good luck
