The following has been copied from an old post (mine, of course) I dug up from one of the popular martial arts forums. It was in response to a question from a TCMA (Traditional Chinese Martial Arts) practitioner, who wanted some tips on how to build up his kicking repertoire.
For the moment I suggest putting aside the “distinction” between sport-kicking and combat-kicking. For instance, a roundhouse is a roundhouse, regardless of whether it comes from Kickboxing, Karate, Taekwondo, Muay Thai, etc.
There are variations, of course. But any kick’s motion, tool surface, angle, etc., can be modified to either serve as a sports-kick or combat-kick. It depends on the objective for which you want to use the kick, which affects the motion, angle and tool of the kick, which in turn modifies how you should drill the kick itself.
For example, people talk about the 45 degree turning kick (roundhouse) used in sport Taekwondo. This kick uses the instep (more accurately, the inner side of the instep). But at times, you can use the ball of the foot. It now becomes a thrust-like kick instead of a snap-like kick. Now you have a cross between a traditional roundhouse and a front thrust kick. This kick can be used both in sport and combat kicking. How well one uses it comes down to how (and how much) one drills this kick in impact-drills, partner-drills and and “simulation”.
When looking for a place to train kicking, check out whether they drill their kicks. If a school simply has its students go through “air-kicking floor exercises” and nothing else, then pass.
If it does a lot of drills with paddles, focus mitts, power pads and heavy bag (plus full-powered, high-intensity partner drills) it could be a good candidate. You might not be able to discover all these in one sitting. You might have to go a few times to check them out (look at their color-belt classes)