@Aaron&Clari
1. Could anyone point me in the right direction to the next steps, please?
P3 instructions for the UK
https://drive.google.com/file/d/1M92AwztXRnkFw6xwUF0ZlntJ6D4-eK2E/view?usp=sharing
Embassy Page
https://uk.usembassy.gov/visas/fiancee-2/required-documents/
https://uk.usembassy.gov/visas/fiancee-2/medical-examination/
London Portal here on VJ
http://www.visajourney.com/consulates/index.php?ctry=United Kingdom&cty=London
London sub-forum on VJ
There are experts over in the sub-forum for your country located here http://www.visajourney.com/forums/forum/99-united-kingdom/ This is where others from your country who are processing or those who have completed their interview and they can guide you on their experience. A TON of information and help there.
A fellow VJ'r who just completed their visa interview
https://www.visajourney.com/forums/topic/690372-my-whole-k1-experience/
Medical prices including vaccination pricing
http://www.visamedicals.co.uk/us-price.htm
Medical questionnaire
https://uk.usembassy.gov/wp-content/uploads/sites/16/2017/05/USA-MEDICAL-QUESTIONNAIRE_IV.pdf
2. I have read about the DS-160, but I need a DS application number, which I do not have.
Use your NVC case number for the application number.
3. How am I to get one?
By calling NVC. Details are in the PDF file found on the first page first post of any NOA2 to Embassy thread. Here is the link to the pdf file.
https://drive.google.com/file/d/1nfin98c33IEpB0T0FlURERriblYmlm5O/view
4. Is this done through the CEAC website - and on that website
No, through NVC. Instructions were given above.
5. is the K-1 classed as an Immigrant or Non-Immigrant Visa (there always seems to be some confusion on this point in some stages)?
Both. As a K1, when checking your case online at CEAC.state.gov you have to select "immigrant visa" as it is treated like as such even though it is a "non-immigrant visa".
Technically the K-1 is a non-immigrant visa but it is treated like an immigrant visa because of the AOS. It is kind of a ba$tard. Non-immigrant treated like an immigrant. Other non-immigrant visas do not usually end up with green cards! The K-1 on its own is a single entry, short time limit visa that expires 90 days after POE. You are a non-immigrant (90 days limit) with immigrant intentions (GC). That is why it is a non-immigrant visa treated like an immigrant visa.
This stage is for those whose case was assigned a case number from NVC and wish to follow the status till it is set to "ready" condition for the interview. You have three stages 1) transit - shipment is in the air or soon will be, 2) received - physical case file is at the Embassy and 3) ready - your case is ready to schedule and complete your interview. These will be your current state or status to your case file once you have received the case number.