The British government is moving to adopt tough austerity measures.
These include making public sector workers retire later and pay more towards their pensions.
In "the day of action" planned for Thursday, some of the biggest strike action seen across Britain in 30 years are expected.
Thousands of people are expected to protest against the changes and cause chaos across the country.
More than 3,000 schools in England and Wales are closing for the day and long queues are expected at airports.
Al Jazeera's Tim Friend reports from London, UK.