Do you think i would win in a fight?

Ok i live in london and im age 15(16 soon) and there is alot of gangs here, They try to rob other people so im scared that they might start a fight with me. Im Overweight I weight 105KG and my height is 174cm. I Usualy lift weights at home do sit ups and push ups. I go swimmin aswell to lose weight. Do you think i could win with 1on1 fight? Im really scared to fight because i might get Beaten up i dont have confidence in myself and im a really shy person..