If it is the first time a person is summonsed to court for possession of drugs they are exposed to the penalties set out under the Misuse of Drugs Acts if they are pleading guilty or found guilty of the offence. That can include a conviction on a persons record with a possible fine or imprisonment depending on the circumstances.
Sometimes as opposed to imposing a conviction on a persons record a District Court Judge may accept a donation to charity to meet the case so that the case either struck out or Section 1.1 of the Probation of Offenders Act 1907 imposed, which is not a conviction on a persons record. However this is never a guarantee and entirely up to the courts discretion. Each case and defendant is dealt with on its own merits and factual background.