It depend what you really wanna lear. To read and write perfectly in Japan or just communicate in this language. If you want both, be ready its gonna take you at least 2-3 year, if your fast learner. In uk there are private school that learn Japanese but itll cost you, and answer yourself this question ,, Am i goin to live in Japan for the rest of my life?"If answer is not, you dont need to learn it. If you wanna be able to talk... watch Japan movies with english subtitles to learn single words and how you suppose to say them.