Scotland's People gives examples of Scottish certificates on their site.
Irish marriage certificates give date and place of marriage, name of bride and groom (their marital status, whether or not of full age*, residences at time of marriage, fathers' names + occupations), names of 2 witnesses, name of officiant.
*this was changed from whether or not of full age to age in years (c1946 for Northern Ireland) and then changed to birthdate (c1973 for Northern Ireland).