JAR-OPS does not specifically prohibit manual landings in Cat 2 conditions; however, the regulations are sufficiently muddled to enable confusion and opportunity for error.
The aircraft equipment requirements for Cat 2 are in JAR-AWO which has been revised such that the costs of certificating a FD / manual approach (flight technical error) are so high that most manufacturers don’t bother. HUD certification is expensive, but worth it if you get Cat 3.
Most of the Cat 2 RVR limits in JAR-OPS are based on an automatic approach with their higher approach path delivery accuracies (low technical error); manual landings may be permitted if the autos fail, but often the regulations do not ensure that the visibility is suitable to continue the approach. In Cat 3 there are specific requirements relating to failures at or below 80% of DH which ensures sufficient visibility for landing – the approach phase is complete.
There are dangers in commencing an auto Cat 2 approach in legal minima, and then disconnecting the autos and continuing manually in marginal conditions - pressing on in circumstances where greater visibility would be safer and enabling earlier flight-path error detection.