In British politics and media, the term "Youth Unemployment" is used to describe 18-24-year-olds who are not in employment - everybody older is classed as an adult. "Adult unemployment" is not normally used as a corresponding term - that is just "unemployment". Some people are of the opinion that this division is for the purpose of making "unemployment" statistics look better than they are, by excluding 18-24-year-olds from the standard figured. Others say that youths who have just left education should not be included in unemployment figures because they have not been put out of work, and finding a job after education does take time, so including them would only skew the figures.
Therefore, "unemployment" in the UK is automatically assumed to be people over the age of 25, not so far off the 30-year-old point you are asking about.
For people aged 45-65, this is termed "middle-aged", and the media do sometimes refer to this group as "middle-aged unemployed" (or "middle-aged and unemployed).
As 60-65 has been the standard retirement age for some time, people over this age are not generally thought of as being unemployed when not in work.