Hello, the CRB check cannot be "ordered" by yourself, but you might have to pay for it.
The employer can arrange it for you and then you pay for the cost, unless he-she will pay it for you.
There is a standard CRB check and the extended or deeper CRB check.
As mentioned above, the information is all on the Web page.
The sad thing is, as soon as you have the CRB check in your hand, it really is invalid.
Because it cannot check in to the future...
But I guess it is the best we can have.
MLA