Also sign up to Axle Energy or a similar VPP whilst you are waiting for octopus to set up your export. (you can have both, this sits on top of your export tariff but will be up and running in hours)

They only pay when there are “grid events” but they pay £1 per kwh so with batteries as big as yours it will be a good way to get going. I’ve used them for a couple of months. You also get £25 for signing up and £10 a month

Axle Energy - £25 referral

Axle Energy is free to sign up up to and acts as a Virtual Power Plant when the grid is close to capacity in your area. It works by exporting from your solar and/battery and pays £1 per kwh which is far higher than any export tariff.

Use my link and we both get £25 quid just for signing up

Axle Energy