Is therapy for me and how can it help my situation?

First of all, congratulations on graduating and starting your new career as a teacher. That is a huge accomplishment in a much needed field.

Therapy is for everyone and can be beneficial in many situations. Yes, it can help your situation too as long as you're ready and willing to do the required work.

What you described in your question sounds like procrastination.  While this skill can be helpful at times, putting things off until the last minute can add unnecessary stress to our days.  Creating a schedule can sometimes help with this. A counselor can help to identify strengths you already possess that will be helpful for you to utilize now. You made it through school and that alone is a challenge. That lets you know you already have the skills needed to manage; you just need to sharpen them more. 

Therapy is good for helping you to improve your self awareness and learn more about you and how you function.  There are resources and tools obtainable to help those who struggle with procrastination. Together your therapist and you can tailor a plan that fits your needs.  You can assess how you got through college. For example, how did you get assignments turned in on time? What motivated you to complete school? Then find ways to implement those skills now or develop new skills. For example, if you have two weeks to complete a lesson plan, incorporating 15 minutes of planning per day could help break it down into smaller more manageable tasks. 

There could also be other areas in your life that contributes to the habits you mentioned. Therapy can help you to explore those areas and find any correlation to how it affects your response now.  That's one result of therapy, being able to understand why you do the things you do. Once you understand, it sometimes helps with making the necessary changes to improve in areas you want to improve in.

Overall therapy can be helpful for you in multiple ways. It's up to you to determine how you want to be helped and what you can do to facilitate that process.  Therapy is what you make it, you get out of it what you put into it.