Ballroom Dancing Lessons in London on Sundays?

Hi, i’d like to learn to dance ballroom with my partner in london on sundays (we only see each other at weekends) and we’d like some classes that arent too expensive that would teach us the basics, like foxtrot, waltz , cha cha etc, for beginners, as neither of us have danced before. but googling is a nightmare- theres so much! are there any online directories or could anybody recommend anything. preferably we’d like to pay as we go. any ideas?