Switching course after Part Is

I am an international student with an offer from Cambridge to study AMES.

Since getting my offer I have been put in touch with a current AMES student and some of what she has told me makes me wonder if I have chosen the best course for me.

I have for some time begun to wonder whether I should have applied to HSPS, another course that interests me deeply.

Were I to ask to switch to HSPS at the end of the first year of AMES, would I be expected to repeat the first year to catch up on the HSPS material? Would the switch be easily approved as long as I am achieving a 2:1 in my first year? Are there some colleges that are more sympathetic to such requests than others?

Thank you very much if you can advise me,