The better broadband for Norfolk (BBfN) site says that parts of Hethersett have been covered from Norwich West. As the exchange is part of the BBfN controlled rollout of BDUK funds they will publicise when it will be updated. As these are council controlled websites they are not always the most upto date and sometimes Cabinets are in place before the website is updated ( or even live).
Openreach can only put it in the lists when approved by the council even if they are already working on it.
Keep an eye on the checkers and the first symptom may be FTTC arriving in the wholesaler checker for your address as coming soon with a draft speed.
If you do this once a week you will get bored the week it goes live! and miss it