Is there something wrong if you are 13 and when you are at school and a teacher you fancy walks past you and you can only think about what it would feel like to have her feet on your willy?

No. Its called a fetish. A lot of people have feet fetishes. A fetish is something that turns you on. If I were you I would not tell your other guy freinds, just cause if they are your age the know just as much about it as you do and might make fun, but dont worry it is very common.