OK, let's get the facts in order here before mass panic sets in amongst photographers.
Quite simply, there is no legal requirement for photographers to have a CRB check. Period. It's as simple as that.
As I have already pointed out, and as Marcel also points out above, as a self employed person you simply cannot apply for a CRB check on yourself. However, as DiddyDave suggests, a professional body such as the SWPP can request a CRB check of you (so long as you are a fully paid up member mind you) - but even then, you still have to pay for this. You should then receive a copy of this CRB detail. If you are employed as a photographer, then your employer can request a check to be carried out.
The decision as to if you should have one or not is entirely yours, your employers, or your clients. If you want one and are self-employed: join a professional body such as the SWPP; if you are employed as a photographer: then get your employer to apply for one; your clients can also ask if you are CRB'd.
Importantly: there is some very misleading information on the SWPP www site which is totally incorrect. It's only a phrase, a single word in fact, but in legal terminology it is extremely misleading. The www site states;
IMPORTANT: DO YOU PHOTOGRAPH CHILDREN?
Have you been checked recently by the CRB?
Who needs to be checked?
Anyone who is working with children or vulnerable adults whether in a paid or unpaid capacity will need to have either a Standard or Enhanced Disclosure.
The item highlighted in bold is simply not true. The correct legal terminology should read;
Anyone who is working with children or vulnerable adults whether in a paid or unpaid capacity may need to apply for either a Standard or Enhanced Disclosure.
There is no legal requirement for photographers to have a CRB check done. I am astonished that a photographers professional body has this incorrectly published on their www site.
If you are photographing children then the parents of course have the right to ask any photographer if they have one, and subsequently they have the right to ask you to leave if you cannot validate or substantiate claims that you do. The law - rightly of course - protects the parents and the children.
In todays day and age, being a member of, or affiliated to a professional body who can obtain one on you is of course a pragmatic thing to do.
But for the SWPP to state that anyone working with children needs to have a CRB check done - is blatantly incorrect.
Being part owner of a pre-school nursery business, and having regularly tutored music students for the local education authority, I have valid CRB checks. As a photographer though, I don't need one per sé.