It is now easier than ever to find new and interesting ways to learn English. With online tuition being available at the touch of the button and a huge array of written resources being able to be stored on the smallest of devices, phrase books and huge textbooks are almost certainly going to be a thing of the past in no time at all. It is also easy to learn online with a real person, but this and the other options mentioned above are likely to be an excellent way to refine your knowledge of a language, rather than the best way to learn it in the first place.
The only way to really pick up the language as it is spoken by those native to a country is to immerse yourself in that culture and amongst those who speak that language as their native tongue. By taking an English course in London, you are far more likely to learn everything you need to know and to do so extremely quickly. Not only might this save you money in the long run, but it will make for a far more effective learning process.
Once you have taken English courses in London, this is where technology will really come into its own. By using things such as book readers to easily carry phrase books with you to remind you of key phrases should you forget, or using your phone and tablets to jot down notes of new phrases you learn as you go forward, you will have a far better chance of keeping the language fresh in your mind for far longer.