Yes, you should continue to learn the theory. This obviously helps you understand the deeper strategic themes of the opening, plus gives you the needed details of the critical lines. Playing the opening in skittles or blitz is a needed to evaluate your opponent’s typical response and will help you create ideas to spring upon them in OVB play.

I once heard someone say that only after you have played an opening several thousand times do you really know it….(probably true…)

In learning the English or other Flank opening concentrate on the “spring board effect” (knowing/understanding when it is the time to push your center pawns)  Many Variations in Flank openings depend on who can maneuver effectively the most. There really isn’t solid evaluations for many of these positions because everything is in flux (It is one of the major reasons I play Flak openings)  For example, Some lines in the following:  Symmetrical English,  Hedgehog, English’s KID just to name a few….a lot of gray areas where he who maneuvers into attack first gets the jump on the other guy.  Start coming up with ideas/plan of getting your forces from one side of the field to the other. Look at how NM’s, IM’s and GM’s maneuver in these positions and keep experimenting this will improve your analytical skills…