After you've applied
You’ll get a ‘declaration of renunciation’ if your application is successful. This will be your application form, officially signed and stamped.
The date your citizenship or status stops will be shown on the form.
Your supporting documents will be returned to you whether you’re successful or not.
Time limits if you’re getting another citizenship
You’ll have 6 months from when you received your declaration to get another citizenship - otherwise the declaration will no longer be valid and you’ll keep your British citizenship or status.