If you don't want to invest in a website at this time then you'll need to set up a Facebook page for your school and a
Meetup.com page. The reason that I keep saying school is because you are the teacher which makes you the school. You just don't have students at this time.
If the term school is uncomfortable to use then use the term "wing chun club." The main thing is that you need some way for people to learn more about what you teach, on their own time without having to contact you directly. A Facebook page + a MeetUp page will allow you to market yourself and your club without spending tons of money.
It may be a slow student build-up, depending on how deep the interest for Wing Chun is, but a slow build-up is better than no build-up. The other thing you can do is to practice your Wing Chun where you plan to hold your class. Even if it's just you in the park, be there at the time the class will normally be there and get your practice on.
And keep any email that you get with people who expressed interest and ask them nicely if they want to receive your club newsletter. If they say no, then lose their email. If they say yes, then it gives you a door way to market to them even if they don't want to do your class, they may know someone who does. Don't underestimate the power of word of mouth.