Look at the travel market in your area. Are there other travel agencies in your town or immediate area? If there are, maybe sit down with them over coffee or an adult beverage and pick their brain about your idea.
If you decide to move forward, maybe do it as a side business while still teaching until your travel agent business can become your main income. There are lots of teachers who have a side business.
Decide if you want to to specialize in general travel, or specific areas or trips.
As the year moves on, more things will start to open up and people are ready to start getting out again. I believe if you are patient, the travel industry is on the verge of resurging and people in that industry will do well.
There are no guarantees. What you have to ask yourself is if the risk is worth the reward for you and your family.
Is being a travel agent or doing another job besides teaching the right move for you? Will changing jobs make you happier? Will it make life better for you and your family? These are questions to look at when considering a career change.
People on the yellowboard can give you lots of secondhand stories about this topic. Most are probably going to tell you not to do it. Do a search and see if there are travel companies being successful during this pandemic and see what they are doing different to be successful.
There have been lots of successful people who were told no but went ahead with what they wanted to do and were very successful.
If this is what is in your heart, and you are willing t put the work in, I say go for it!