If I have excess fat around my thighs, how can I make sure that I get rid of the fat there rather than somewhere else?

    You can't. There is no such thing as spot decreasing, which is probably obvious to you by now because your thighs generally move more than any other body part but the fat still ends up there. As you maintain a calorie deficit “eat less than you burn”, body fat will leave from whatsoever area your body was genetically programmed to draw it from. As a rule of thumb, last place on is the first place off. All that said, if you maintain consuming fewer calories than you burn, that stuff on your thighs will go, it just might be the last place it disappears disappear from.