Yeah! you can be a primary teacher after your BSc Physics but you need to complete the course of BEd after your BSc in Physics. Now if you feel tough in Physics, then apart from it choose any other course which you like or interested in. because BSc physics is tough and you need to feel interested in the subject, in order to do good in the examination.

Now its your choice.

For more information regarding the BSc in Physics consider the link below:

https://www.careers360.com/courses/b-sc-in-physics

For more information regarding BEd consider the link below:

https://www.careers360.com/courses/b-ed-bachelor-of-education

I hope this helps. Wish you a great day!