Interview times in the UK???

[Canada09]

Hi,
Hopefully someone can answer our question. I have been accepted as a sponsor for my husband. We are currently living in the UK applying from here.
He received a notification mid-July that he will need an interview and will need to bring missing documents but they have not given any times.
Has anyone been asked for an interview in the UK? If so, how long until they gave you a date and time? and How much notice did they give for the interview?
Also, after the interview, how long did it take for them to approve the application and have your passport stamped?
Thank you in advance for all your assistance.
Canada09 (hopefully)