Being in the south east, near London, for me the most noticable changes are:
Ethnic mix - 20 years ago most black people in the UK were of West Indian descent. Now there is a big proportion (larger in my perception) of African and African descent. Also many more East Europeans due to the change to immigration law/EU etc. Not saying either of these are bad things, it's just a change. Oh - and over here 'black' is the preferred term (in case any USA people are offended).,
High Streets - high street retail is visibly dying in many towns, with moves towards large retail parks and shopping centres (malls) way bigger than anything we had 20 years ago.
Wider choice of foods in supermarkets and availability of things that weren't even heard of (likewise I suppose other things less available as they go out of fashion) for example I had sweet potatoes and plantains last week, but would not have found them in the past.
Building development - lots of new housing on types of land that would not have been built on before (lots going up on flood plains near me, will be a disaster at some point). Think that development is a bit more sympathetic to surrounding buildings nowadays, more emphasis on preserving historic centre atmospheres, you see some 1970s monstrosities squeezed in among centuries old buildings, for example, but now even contemporary designs need to fit well into their spaces and add something if it's an interesting area.
Work - unions much less powerful so some employees in less strong position than previously, but on the other hand other 'workers' rights' are improved, for example minimum wage, paternity rights and so on.