What gas work can I do myself?
Operators of gas cookers can perform tasks set out in the instructions provided by the appliance manufacturer. These are common maintenance tasks that are intended for the owners to carry out. If it is set out in the manufacturer's instructions, it would not be a breach of the law.
The law allows you to replace or adjust any component or control that is designed to be operated or replaced by the gas consumer. For example a cooker control knob.
However you should not do anything that involves disturbing the gas carrying components or that could affect the combustion process. For more clarity please review the Gas Safe registers' fact sheet.
Gas Safe Fact Sheet