Hello aspirant

Yes you can prepare for UPSC side by side while doing Psychology honours It would be beneficial for you.You can take psychology as a  optionalsubject in UPSC. It is of 250 marks paper. If you score good in optional.

Eligibility criteria for UPSC:

1.Candidate should have abachelor degree from a recognised institute/university.

2. The candidate must have attained theageof 21 years and must not have attained theageof 32 years .

Hope  this answer is helpful for you.