I don't have any experience with this, but it looks like it is highly preferred to try the cream first. Check out the last paragraph where surgery on an adult can change how they experience sex. I would be asking the doctor about that.
Treatment with steroid cream helped the phimosis to go away completely in about 44 out of 100 children. In some of the other children the treatment was at least able to loosen the foreskin somewhat.
No side effects of steroid creams were observed in the studies. While phimosis is quite likely to come back after some time following treatment with steroid cream, the treatment can be repeated several times. If phimosis still persists, or pain or complications occur, surgery may be a good idea.
A number of studies have shown that circumcised men generally don’t seem to be any less satisfied with their sex life than uncircumcised men. But the role that the sensitive foreskin actually plays in sexual experience hasn't been fully explained. Circumcised men might be more likely to have problems during sex if they had the operation as an adult. So before a circumcision is carried out, doctors explain that sex may feel different after the procedure.