scary We would remain a member but we would need to renegotiate all the schedules as our membership terms are bundled in with the EU's terms. Whilst all 28 EU member states are individual members, the EU itself is also a member. The EU member states therefore have combined “rights” (e.g. to be able to export to other countries, and not to be discriminated against), balanced against shared “obligations” (e.g. to open up to imports from them, and not to discriminate against them).
Here's an example of how complicated it might be:
In the WTO, the EU has agreed to keep its import duties within certain limits. For example, for some types of shoes this is a maximum of 17 percent. That limit applies to all EU members when they import from outside the EU. The EU’s quotas — allowing quantities of certain products to be imported at special lower-duty rates — are for the whole single market, not any individual country such as the UK. Limits on agricultural subsidies are also for the entire EU.
To be an independent WTO member, the UK would be creating its own rights and obligations out of the EU’s. That’s not as simple as it sounds. One reason is because other countries with different interests would want to ensure the balance is also right for them.
Take just one hard-fought issue: low-duty import quotas for high-quality beef, just two of almost 100 EU quotas. The EU opened these beef quotas after lengthy negotiations with Argentina, Australia, Brazil, Canada, New Zealand, Paraguay, Uruguay, and the US.
Extracting UK beef quotas out of the EU’s would require negotiations with all of them, plus possibly other suppliers such as Botswana, India, and Namibia, and definitely the EU itself — Ireland, Germany and France have particularly strong beef lobbies.
While the exporting countries are pressing for the UK’s quota gates to be opened wider, and jostling with each other for paths through the opening, UK farmers would be pushing in the opposite direction. Remember, to reach agreement, the WTO’s consensus rule would apply.
www.ictsd.org/opinion/nothing-simple-about-uk-regaining-wto-status-post-brexit makes interesting reading on just how complicated things may be if Brexit goes down the WTO route. Note the section about the level of uncertainty over what the EU quotas actually comprise.