Tempted by CC cash->PB stoozing

My CC is offering me a 0% cash loan for 1.5 years, with a 3.3% one-off transfer fee.

Taking this to max and investing into premium bonds for the same period should give an expected annual return of about 4% including an upside to a lucky strike.

Monthly minimum payments apply, but would not be a problem.

This would not be a big sum though, about £3500. So if no premium bond wins at all over 16-17 months, would lose about £115 overall.

Thoughts? Expected return is still positive.