Flexible working refers to any working arrangement that is different from the default arrangement in your workplace or which would otherwise change your existing working arrangements. Working from home, working part-time, annualised or compressed hours, term-time working and job-sharing are all examples of flexible working.
As long as you've been in your job for at least 26 weeks and have not made a flexible working request in the past year, you have a statutory right to make a request. If you decide to make a formal request, use a Flexible working request letter. This will set out your new proposed working pattern and suggest how the business can deal with any disruption which could result from this different working pattern.
Some employers have a Flexible working policy which clarifies the process of making and dealing with requests.