Hi Laura
Learning to dance will be one of the best things you can do, it will not only keep you fit and healthy, but you will thoroughly enjoy it!!
You dont need a partner to learn, however, find yourself a good teacher where you can get a combination of individual lessons and group classes. It is always better if you can do both.
In your individual lessons find a teacher who can give you the feeling and correct many problems before they arrise.
Use the groups to reinforce what you have learnt and to learn step patterns and also to get the feeling of dancing with different partners.
Find dance parties which you can attend, as the more often you dance the better it is.
Basically you are learning a muscular training, like riding a bike once you get the feeling it is fun.
Look in your local telephone diretory or contact IDTA or ISTD to find a list of qualified teachers