It’s about people being free to access all lawful internet content equally, without broadband providers discriminating against particular services or websites. – What is Net Neutrality, Ofcom
The document sets out the requirements that your provider must follow. These follow the EU rules on Net Neutrality. The requirements are to not block or slow down access to particular sites. Nor must they gain commercially by manipulating or redirecting traffic to alternate destinations.
The provider will give information about how they conform to the rules; what their traffic management policies are; if there are any data caps and at what levels; what your download speeds are against the advertised speed. They should also detail how to get redress should you find a discrepancy in real-life.
Ofcom also list the process you follow when you have a complaint. This includes you checking a few things in your environment. This is to first contact your service provider, and then follow-up via Ofcom if needed.