Even though you have not had symptoms, you can still pass the virus to others. You must still follow the ‘Self-isolation’ and ‘Ending Isolation’ advice as linked above.
The date your COVID-19 test was taken should be used as the first day of the 10 day self-isolation period. If you subsequently develop symptoms within that 10 days, then use the date of onset of your symptoms as the first day of your self-isolation period. The same date is used as the first day of the 14 day isolation period for your household members.
COVID-19 is a new infection, and we are discovering more about it over time. At the moment, we do not know if you can get COVID-19 again after recovering from it.
Therefore, if you develop further symptoms consistent with COVID-19, the current advice is that you and your household should self-isolate again and you may request a further test.