Can you afford to use a gym? Some let you join for just a month. Some let you pay as you go.
Of course there might be no such gym within a reasonable distance of your house/work.
Municipal leisure centres are more likely to give you these options.
Failing that, then finding a sports field and running with trail shoes on snow covered grass can be a safe option (even if you fall, then it's usually not the end of the world)
But at the end of the day, if you're not comfortable you can run safely, then don't run and just accept it as part of life! Good luck