There are many excellent resources out there for practicing English grammer for free, including Duolingo and Babbel. While these don't offer the same individualized instruction and natural conversation practice of a dedicated teacher, they can help keep your grammar knowledge sharp and give you consistent opportunities to practice reading, listening and even speaking. I use Duolingo pretty regularly for learning Russian and have found it to be a good tool. It also offers a free test for helping to assess your level: https://www.duolingo.com/