There was no option for age 25-30.
I find Cadbury World on the whole, incredibly dated.
When did you last visit?
In the last 5/6 years they have upgraded it with Essence, Purple Planet, The Bournville Experience and most recently with Advertising Avenue. They also re-did the Jungle section with new scenes and waterfalls.
Each of these sections are pretty good and highly interactive, although Essence is probably the weakest of the lot.
Parts of it are dull though yes - nothing much happens in the demonstration area these days, there's not enough to see in the packaging plant and there's not half as many freebies as there should be. The shop is overpriced too and should be much bigger.
Overall though I would say it is the best non theme park day out to be had in this country.