There are no serious errors here. But there some awkward / unnatural bits, including:
* "to teach across the age and ability range" bakes the question "what age and ability range?" - obviously this is information you have provided in brackets next, but the way that sentence was worded with the definite article ("the") is as if the information has already been established. So I would reword using the indefinite article ("a") roughly as follows: "to teach across a range of ages and abilities (children, teens and adults; Starter to Advanced levels)" - this now sounds much smoother.
* "our cohesive staff team" sounds odd because "staff" and "team" have a similar meaning so putting the two words together is a bit overkill. Consider changing it to simply "our cohesive team".