I'm in 11 science with maths.Can i prepare for upsc with english honors?

UPSC academic eligibility states, 'Candidates need to be graduate in any stream for appearing UPSC Civil Services examination. Those candidates who will be shortlisted by the Commission for taking the Civil Services (Main) Examination will be required to produce academic proof of passing the requisite examination (Graduation Degree Certificate) with their application for the Mains Examination.'

Therefore, you have to be a graduate to apply for the exam.

On the other hand, If you opt for full time English Hons and study for UPSC at the same side that will be good but then you should be able to balance both.  You can join a part time coaching for UPSC preparation and prepare keeping the both aspects in balance. Go through important topics in NCERT and work upon your reading skills which is quite common habit and won't interfere with your graduation.

Get updates, information on topics like sports, literature, culture, history, geography, economics, politics, national and international affairs.

If you still feel the guidance is required, then join a professional coaching academy for the preparation.

Good Luck.