Account report - Tax help

Hello. This may be simple for the tenured Amazon businesses out there. I am a sole trader (self assessment etc) and only been doing the 6/9 month's full scale.

I kind of know about how to do my taxes and can source help for assessment etc.

I just want to know a couple basics.

Do you run a sales report 30 days after the tax year ends (UK 5th May), this is when orders cant be then returned etc?

How do you run an actual report. I just need the basics. Sales minus what was cancelled, returned etc minus any other fees. Shipping (via Amazon just VAT if linked royal mail account), Amazon fee's and customer order adjustments, chargebacks.

I seem to only be only able to calculate my earnings by manually adding up all disbursements, which seems wrong. Also how can I run a report over a period of time for disbursements?

Once i know exactly the bottom line from Amazon I can calculate my expenses and product costs externally.

While we are talking tax, I know there's a lot of Amazon online accountants who will link your account etc and help. I want a UK based team, something with a fair level of customer service. Any recommendations just in case i don't go ahead and do it myself.

Thank you for reading this far