well i actually got this email from them
Dear xxx,
I assume that you have been successful in obtaining a place via the EAS system? Even with that benefit it will be extremely difficult for you to transfer to a CSP place next year. The requirements change from year to year depending on the other transfer applicants, but as a guide you would need to obtain at least 8 distinctions, and possibly some higher distinctions in your first year to be competitive. Unless you are able/willing to pay DFEE for the full 5 years I would strongly recommend that you consider accepting a CSP place for one year and then applying to transfer.
btw what's the percentage for a distinction and a high distinction? thanks!