If you want to go from B1 to C1 in two years, you're going to have to work a lot harder than 3 hours per week. Unless you have a real talent for languages (and depending on what your goals are), you should probably think about close to 1 hour to 1.5 hours a day. This would be a mix of all kinds of language learning - 3 hours at school, listening to English on youtube/the radio/television, reading, writing and speaking, as well as the usual learning vocab, revision of grammar and so on.
It's do-able, but 3 hours a week won't get you what you want.
Put it another way, students generally do 3 hours a week for FCE(B2)/CAE(C1), but without doing a further 3 hours at home per week, they'll have to be lucky or talented to pass.