Just a cautionary tale: I had a wedding couple come to me last year. They had set their hearts on Viennese Waltz, but had only two weeks to go before their big day, and could only make time for two lessons.
Neither had danced before, and the groom, finding the rotation of the dance baffling, lost his temper half way through the second lesson, and he stormed off! She was acutely embarrassed, of course, but these things happen.
Give yourself plenty of time (several months, ideally) and work with an experienced instructor. You can space out a handful of lessons (and therefore contain the cost) as long as you have a specific practise goal, after each lesson, and you then make time to practise, practise, practise....
A simple combination of Reverse (Left) and Natural (Right) Turns, separated by Change Steps, is all that you will need, but an instructor will also show you simple ways to start and end your dance that are a little more elegant than, well, just starting and stopping.
Good luck, whatever you decide.