British Embassy in Micronesia
All the following countries make use of the Fiji Embassy. These are the British Embassy in Tuvalu as well as the British Embassy in Marshall Islands and the British Embassy in Tonga as well as the British Embassy in Kiribati. However, the Federated States of Micronesia, which is a sovereign state within Micronesia, consists of four states, and each state comprises a number of islands. Likewise note that the four states of the Federated States of Micronesia are Yap State, Chuuk State, Pohnpei State and finally as well as Kosrae State.
If you want to renew your passport then you will have to do this online. Note the posting about passport renewal on this website listed here. If you have a BNO passport then you can see the post here on BNO renewal.
Register a Birth Abroad:
The British High Commission does not deal with this and you will have to do it yourself. You need to download the needed documents and send it back to the UK for processing. You can see the born abroad post on this website here.