I'm in my late 20s and used to live in London. Moved my things out of my flatshare and into my parents' place last year.
Since then I've been bouncing around different countries but have found I really like Porto, Portugal. My cost of living is roughly 33% of London (for example: rent, housing taxes and utilities costs in London were £1100 - I'm paying £350 total in Porto). At the same time, the quality of life here is superb.