So far I've got to the end of John Thompson Easiest Piano Course book 1 and can play all the pieces perfectly.
So far I got as far as C#. Where is that again?
Tell me this is a joke. You got to the end of book 1, can play all the pieces perfectly, and you want to learn that concerto? I'm studying in a conservatory and I dare not even try it yet. That's one of the most difficult concertos from the piano repertoire. And it requires a lot of stamina (physically and musically) to be able to pull it off. If you really want to learn a concerto, may I suggest that you try Kabalevsky's Concerto No. 3 ("Youth"), or some Haydn first? Those are among the lightest concertos, and most students start off learning those before going on to bigger concertos (the Schumann A-minor isn't small, by the way. Neither are any of the Beethoven concertos).