Database design help needed please!

Hey guys, I'm new to this forum so firstly hi, it's great to find such great place!

So my issue is I'm trying to design a database system for a website I intend to implement, its for booking and viewing appointments, I've done a lot of work in terms of what I want it to do and have the knowledge to do it, I just want some input into my database design.

Okay so I have 3 tables, membership, availability and appointments, heres what they look like so far:

Membership table:

MEMBER_ID
FIRST_NAME
SURNAME
ROLE
EMAIL
EMAIL_ALT
PHONE
OFFICE

Availability table:

MEMBER_ID
DATE
TIME
LOCATION
STATUS
AVAIL_ID

Appointment table:

MEMBER_ID
DATE
TIME
LOCATION
STATUS
APP_ID
AVAIL_ID


The idea is that a member registers (details held in membership table), then they then define their availability (details held in availability table). Now, they may book appointments with other members and other members may book appointments with them, provided that the time they book is available according to the availability of the member they are trying to book with. (Sorry if thats a bit confusing)

Anywho, my question is, am I missing anything that is necessary? or is there anything redundant in there that is not needed?

Thanks for any advice or pointers, I'm kind of new to databases!