Dear James DaviesUK,
Good day! Thank you for posting to Microsoft Community. We are happy to help you.
I'm sorry to hear that you're having trouble with the "Send Availability" feature in Outlook for iOS. Microsoft has recently made some changes to the app, and it's possible that this feature has been removed or moved to a different location.
To confirm, the "Send Availability" feature has been removed from Outlook for iOS. However, you can still share your availability with others by creating a new event in your calendar and inviting the person you want to share your availability with.
To do this, open the Outlook app and tap on the calendar icon at the bottom of the screen. Then, tap on the plus sign in the top right corner to create a new event. Add the details of the event, including the date and time, and then tap on the "Invite Attendees" option. From there, you can add the person you want to share your availability with and send the invitation.
I hope this helps! Let me know if you have any other questions or concerns.