The answer is no, you cannot complete a CPL(H) course without the 5 hours of night flying unless you already hold a night rating.
Appendix 3 K. to Part-FCL, para 10
Applicants without a night rating helicopter shall be given additionally at least 5 hours night flight instruction comprising 3 hours of dual instruction including at least 1 hour of cross-country navigation and 5 solo night circuits. Each circuit shall include a take-off and a landing.
As Whopity has already indicated, the UK CAA does not have the power to exempt anyone from the Regulation