Higher Tax Rate Relief for SIPP Contribution

I am an employed higher rate taxpayer and I made a SIPP contribution back in March. I got the standard 20% tax relief at source automatically, but I've been trying to figure out how to claim an extra 20%. According to the government guidelines on pension tax relief (https://www.gov.uk/tax-on-your-private-pension/pension-tax-relief ), it seems like I should be able to get it via Self Assessment tax return form. But here's where it gets confusing: On one hand, it says I need to do a Self Assessment tax return form. On the other hand, another part of the website (https://www.gov.uk/self-assessment-tax-returns/who-must-send-a-tax-return) suggests I do not need to do one. Despite the confusion, I decided to submit a tax return online a couple of weeks ago. However, I haven't received any acknowledgment or indication that the application was successful. Additionally, there's nothing showing up on my Government Gateway account. So, here are my questions: How can I go about claiming that extra 20% tax relief for my SIPP contribution? If I do need to use Self Assessment tax return form, how can I check to see if it's been processed? Any help or guidance you could give me on this would be super appreciated!

Hi kate howe,
You can check if you need to file a Self Assessment here:
Check if you need to send a Self Assessment tax return
If you do not meet the criteria then if you contact HMRC we can review the relief claim:
Income Tax: general enquiries
If you do meet the criteria and have not yet heard back from your submission you would need to contact HMRC to review. 
Thank you.