Shared pathway what are my rights?

I share my front pathway with my next door neighbour and she has recently put up a gate which i had no problem with, but now she has put a padlock on it and only has 1 key. On numerous occasions i have found myself unable to get in as she has it locked and when people come to visit me i have to rap her door to ask her to open the gate, surely this shouldn't be allowed. I have lived in my house which i own for 37 years and her house is rented off the council.