What do I need to extend my VOA in Thailand, and when should I do it?

Visa extension UK Passport

Hi all , I’m currently here on a VOA Visa having previously had a 90 single entry Non o Visa

Does any one have an up to date of the list of things I would need to take with me to Laksi immigration in Bangkok to extend for another 30 days , and also how soon before the end of my current VOA which is 16 th April

This would help me greatly and give the Airlines time to sort out their act instead of just cancelling paid for flights and being told to contact your travel insurance for a refund

Many Thanks