Clearely if a householder wanted his/her consumer unit to be attached on a "meter board", that is flameproof board, and to mount it on stand-off insulators / shoulder washers - it would not be breaking the law to affix the new board to the wall.
If you are talking about a consumer's own, separate 'new board', then a consumer is obviously free to attach whatever they want to their wall and then attach their own equipment (CU etc.) to it - although I'm not sure why they would want to use stand-off insulators etc. Even if you want to create a space behind the board for cables, there's no real reason to use insulators (unless to protect the material of the board from rotting due to a very wet wall!) - any sort of 'standoff' would be adequate.
What a consumer is
not allowed to do is to interfere with in any way, or attach consumer's items to, the DNO's board.
Kind Regards, John