I was going to make a whole lot of comments but I will just try and sum up the story so far as best I can. you seem like a good writer but this story has a few holes in it… holes the size of London, there are so many things that don't even come close to adding up.
muggle UK legal system is just as corrupt and incompetent as the Magical UK system, Figg never tells Harry about being magic despite it being Obvious Dumbledore could care less about him being in prison at the age of 6 for something he did not do. Dumbledore does not send him his letter and no one in the wizarding world questions the absence of the B-W-L. he turns 15 and for some reason presumably Voldemort resurrecting so the wizarding world decides… "let's invite Harry to Hogwarts now" He reads about how it was Dumbledore who know where he was but never really questioned anything like why he was totally ignored all those years. then he meets some of the quality instructors at the school that it is taken for granted he will attend, and is adamant that he has not decided to do so but then he just changes his mind and he will go to Hogwarts despite knowing nothing.
he reads a few books and BOOM is caught up to the others his age. and after 15 years of neglect and being ignored by the wizarding world says "Yes I will help fight this dark lord of yours for you."
does that about cover it?
I don't even get your Dumbledore he clearly knew Harry was in jail yet talks like he lived with the Dursleys despite Sending Tonks to the Jail.