From 1 March 2021, if you’re a member of a household, childcare bubble or support bubble of staff or a pupil you can get a twice-weekly test:

Through your employer if they offer testing to employees
At a local test site
By collecting a home test kit from a test site
By ordering a home test kit online
Guidance/rapid-lateral-flow-testing-for-households-and-bubbles-of-school-pupils-and-staff 
The idea is that although primary pupils aren’t tested their parents/carers can be to help keep staff and other pupils safe

An Introduction to Rapid Self-Testing for COVID-19

How to Do a Rapid COVID-19 Self-Test

NHS, Test and Trace, How To Flyer for Primary Schools & Nurseries

A guide to regular testing for parents with children at nurseries, schools and colleges

Instructions-for-covid-19-self-test