ya, just take advantage of what you can, the more martial arts you can master the better they will ALL help. Maybe not the best as another has said but my personal favorite would be ji jitsu, I’m personally not quick enough for taekwon-do….if you are then go into some of the others that take advantage of quickness. Try some kick boxing….
sounds like your weight room is a little dilapidated, which probably means they don’t really care who goes in there maybe? I would just go in there and start lifting like a mad man, make up your own lifts that will best suit your fighting style. For instance my style was to get what ever limb I can grab and lock it down and break/or suffocate. If you like your current style, hold some low weights and try punching. Quickness would probably be your biggest advantage, so low weights as quick as possible with all the usual routines (curls, overhead press, triceps press, pushups with maybe some weight on the back, squats/straight to pushups without any weight, kicks with maybe heavy shoes or if you can find them those weights you put on your ankles.)
If you could hit them one time real good in their temple and knock them out they will probabkly never bother you again....but who knows no bully is the same and I don't know your exact situation. They might just come back stronger and bring 40 people or some BS like that...
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“It is better to offer no excuse than a bad one.”
― George Washington