Do recruitment people have the right to force applicants to disclose about their convictions?

Actually, if an application form or an employer asks an applicant whether he or she has a criminal record, he can say "No" if he or she has already spent his or her convictions and if the job is not excepted from the Rehabilitation of Offenders Act 1974.

If the offender has unspent convictions and if he doesn't disclose them when asked to, then he can be dismissed by the employer, and if the employer pursues further action, he can also be prosecuted.

It is always best for employers to consult with a legal adviser or an attorney if they had to deal with an ex-offender. This helps them know their rights as employers and of an ex-offender's right as an employee or an applicant. Ex-offenders should also know their rights.

How long does a rehabilitation period last???

It actually depends. From what I remember, you only needed 6 months as a rehab period for any absolute discharge

Yup. Prison sentences of 6 months or less have rehabiliation periods of 7 years. If it's more than 6 months to less than 2.5 years, it's 10 years.

That's partially correct. 7 years and 10 years are for those who are 18 years old or above. For minors, it's half of that.

Wow, that is a long time

It is. Crimes wherein you have to pay fines had a shorter period though. 5 years. This includes community service, drug treatment, reparation orders. For minors it's 2.5 years.