First I congratulate you on not only taking the challenge of gaining employment but considering the actual process and issues we all should consider. I have a lot of recruitment experience - some say hiring / firing, and personal development of employees. I actually tried to have an intellectual and fact based conversation with my Probation officer about this subject: obviously I was wrong.
First: Read the advert fully and as you mentioned, only apply for roles that you do not have restrictions against; if necessary call the recruiter under the guise of getting the required references ready to see if there is restrictions. This is also accepting that you will not get security cleared for instance.
Recruiter: On their receipt of your CV the recruiter may have a discussion with you for various reasons, which will not be face to face. To me I do not like to disclose to them unless directly asked. If asked I make a decision to say either ' due to confidentiality reasons I am willing to discuss this at interview and would a unspent conviction stop me being employed?', or confirm confidentiality and disclose the minimum. Sometimes the recruiter knows ex-offenders are not acceptable but does not mention in the advert. Also if I know I have to disclose to them I use the same manner as I will with the face to face interviewer. Remember you may not get this role but if the recruiter accepts your experience and seems to be sympathetic they may come back to you with more suitable roles. Also if you do disclose, ask them to disclose to the firm wanting to fill the vacancy and confirm back to you they have done so. They may say they will but I have attended 5 interviews, been offered the job but then it is rescinded as the recruiter had not informed them and I was not asked at interview.
You do not mention if you was incarcerated? If you did then do not give the prison name or mention it (that is not a disclosure requirement) e.g. just say various locations. However do list the roles and responsibilities, any educational courses you did as this shows you have been productive. If they are interested they will ask questions at some stage in the process about this period and then you can disclose.
In regarding the disclosure, I have always first asked / confirmed that any information will be held in confidence and only seen by those necessary. If they cannot guarantee this then you have a choice, end or continue with the interview. Be confident in yourself and possibly have a bulleted note to help with your disclosure but do not hand them a document. You will loose control of the document and may not get it back at the end of the interview.
As with everything about the interview, they are looking at your character and presentation and being able to talk about your offence is one way of demonstrating your rehabilitation and acceptance of your mistake and learning to improve.
Hoping you are successful, accept that the PPU may call them so ensure you are honest to the interviewer about the charge you are convicted. However keep it simple and to the point. Do not try to give excuses or mitigating circumstances as that will lower their confidence in your honesty. Do tell them about the manner you have pursued the understanding of the reasons for the offence and positive controls you have now to stop any re-offending.
Have the details of any organizations or mentors that have supported you and willing to speak on your character. This is different from the normal references you offer and should only be given with their approval and if appropriate.
Most important point though is look at them to understand their reactions, listen to their words as they may be trying to stop you mentioning further details out of respect to you. At this point they will know if they want to hire you and what their processes would be considering the offence.
Finally know that the CV is just a possible character that may or not be a suitable fit in their bigger jigsaw puzzle of a business. When you walk through the door they will see a presentation image of the character and that may discriminate against you without you speaking. Both though first two hurdles can be passed over by the third and most important hurdle and that is you.
Believe in yourself, accept the past for what it is as it cannot be changed, focus on today by setting and making achievements for today. Tomorrow is just another day of you setting and making achievements not for reflecting on past errors as your today's achievements show you are a success!
Good luck for today, be compassionate to others no matter their offence, and remember you are an ex-offender, a human being and have a life to live not only for yourself. but also those who love you.
Learn from yesterday, live for today, hope is for tomorrow else what is left if you remove a mans hope.