Service providers have up to 5 days to provide it, I expect you'll probably get a call from the cancellations team today to see if they can persuade you to stay.
If the reason you are leaving is price have a chat to them, they maybe able to help, they did in my case.
Virgin (ADSL) => Namesco => Newnet => O2 => Plusnet => Zen => Newnet => Zen Lite 8000
Note: I don't lay turf for anyone. astro or otherwise, all views and opinions expressed are my own based on experience.