If you really believe you could outperform a Managed Fund by investing yourself, you could transfer it to a Self-Directed Personal Pension which will allow you to choose your own shares (or property if the fund size is sufficient) within your Personal Pension policy.
You should check the following with BIAM - (1) is there an ongoing monthly policy fee, even though the fund is paid-up, (2) what's the annual fund management charge and (3) would there be a charge for transferring to another provider.