A little update: Returned from holiday to find my acknowledgment letter and biometrics letter in the post, dated March 23. Decided that I love Luton so much, I went back a second time today, as they have the most convenient biometrics post office (took the train, wasn't keen on driving to the MK which in theory is closer). Anyhow, the Home Office now have my biometrics and a signature that, after three attempts, looks like an impressionist painter had a few too many and then tried to forge my signature. If you squint, you might be able to see a resemblance. Oh well!
Basis: Unmarried Partner visa, 5 years residency
Applied via post: 12 March 2016
Application received by Home Office: 14 March 2016
Fee charged by Home Office: 31/03/2016 - This was the date the checque cleared my account, they said they had received full payment in their letter dateed 23/3/2016
Email acknowledgement: none
Letter of acknowledgement: Dated 23/3/2016 - Received between 29/3 and 1/4/2016
Letter requesting biometrics: Dated 23/3/2016 - Received between 29/3 and 1/4/2016
Biometrics enrollment: 07/04/2016
Approval received: TBD
Ceremony booked for: TBD