The welcome email was sent to you from support@velosurance.com and a search of your in-box for that specific email address should result in finding the policy documents. We also maintain an active chat line @ Velosurance.com and you can request your policy number via a chat during normal business hours and if we miss your chat we will always respond via email from the chat page.
To retrieve your policy number please submit the email address you provided when you purchased the policy. You might also search for your policy documents that were attached to the welcome email that was sent to you on the day that you purchased the policy.