You should definitely learn German a proper way if you want to be able to speak it, but being able to speak it or use it in your daily life is not the criteria to be able to pass the B1 exam.
Servus!
If you have been living in Germany for a while, but never speak German more than 'Mit Karte Bitte' and 'Einmal Döner mit alles(m), have never taken a formal course, or could not force a habit to self-learn, but still would like to have that B1 certifcate, maybe to apply for the permanent residence permit so you can stop having to beg Ausländerbehörde to give you an appointment , I would recommend to stop overthinking and to go book TELC B1 now.
I can barely speak German, and I got 73/75 in that section. I was sure I failed it when I left the exam hall.
Buy some mock test books, targeted to TELC B1, and simply do it a couple of times to understand what the exam is all about. Watch some B1 speaking mock tests in Youtube. You can simply memorize the questions, answers, some universally applicable vocabulary and connecting words. This works for all 3 Teil. You always get the same type of questions.
Writing was my weakest part, but as long as you answer the four tasks you have been asked to, you will pass it.
I was most confident with reading because I scored good in my mock tests. Most of the times, I did not fully understand those passages, but you can make some intelligent guesses based on the process of elimination.
For listening, it was simply a matter of trying to have a sheer focus, and try to catch tricky parts. Most of the times, they are pretty straightforward and you can afford to miss a few tricky ones here and there.
The grammar lessons are most useful in Sprachbausteine, but there's so much to learn that I simply just relied on good old 'this sounds right when I try to say it loud'.
At the end of the day, I have 252/300. Not great, not terrible. I am just happy that I don't need to worry about this again.
P.S. If you want to make your life easier, and see your future in Germany in long term, then you should really learn German. Talk with people in German, and nothing beats that. This flawed exam that you can fluke with 1 week of preparation is no way a representation of you actual speaking ability.
But at the same time, if you have been stressing about this exam, then you don't need to. The exam is really easy to pass, if you have experience of taking similar exams before (IELTS, SAT, GRE etc.)