I can understand why you might think it is but try to look at it as another tool in your box as a musician. After all, if you understand music theory, then you will understand a great deal more about how your pieces are written, what scales do etc.
Theory actually helps you as a musician - it's not just an exam to be struggled through in order to steam ahead into higher grades of instrumental/vocal exams.
Later on, if you take GCSE/A level music, you may be very glad you've got the theory knowledge you have - and even if you don't do these exams, it's still going to help you longer-term with your playing.
I try to encourage my students to see passing a formal theory exam as an exciting challenge not as a painful, boring experience.
Hope you get on well with yours when you take it.