Soldato
Had to do one for the scouts camp I was going on with my kid but since I'm as good as gold I had no worries. I got a copy though.
When I had my ECRB it had all the stuff from when I was a young I.e <17 they won't tell your employer what you have on your record but they will inform your employer that it has been flagged providing its something minor and expect a meeting with HR if you suspect something might show.
I'm ECRB cleared and can work in schools and govt buildings and I have assault, criminal damage and obstruction on my record from when I was about 15/16. Providing you have nothing serious or recent (will straight up fail the crb) and can show you are not a risk then your employer should be fine
It is worth noting that violence related crimes, no matter how minor, can often bar you from working with vulnerable people but it does rather depend on the company. Also once you get your copy back you will know for sure what does and doesn't need to be declared.
A former colleague had a client who declared some quite serious offences but overlooked a comparatively minor one. However when her ECRB came back showing the minor one she had forgotten to mention she was instantly dismissed because she had 'technically' lied on her application and they were left with no option but to dismiss.
www.apextrust.com can sometimes be of use too.