Hi,
It is possible, but normally for working pros, or ams that claim to be working pros. Football at a league matches will be almost impossible without registereing with the FA as I beleive all the imaging rights remain with them. Sunday league and the like just needs the permission of the team managers, (and parents if the player are under 18)
Concerts, I haven't done many - but the standard rule is you might be allowed access, but normally for the first three songs, then you get moved away. They are looking to protect the image rights of the artist.
The main way that you get access to events is to be "accredited" which means that a publication asks the event organiser if they can send a photographer. They give them your details, then the organisers allow you to collect a pass at the event. That way it keeps hundreds of keen amateurs out of the way.
Good luck in getting your passes
Hope that helps,
Gary