I royally messed up

I know that the tax office has no time for excuses, but I’ve had a shitty year and filed my tax return in a rush. I made mistakes and am now being questioned and asked to provide proof. As well, my laptop broke so I no longer have my expense or income spreadsheets. I’m so scared. I’ve used an account for the last few years but thought I could do it myself this time. Obviously not. Now I’m ashamed and embarrassed and don’t even wanna tell my partner. What do I do?! Any advice?? I’m in the UK, thanks.

EDIT: My partner also doesn’t know what to do about this. The tax office contacted me as I didn’t know I made a mistake. I tried to answer their question about my self employed work and that was ok but they then questioned where I included my other self employed work. As I haven’t got any records now, I’m panicking. Does anyone know what might happen to me? I don’t have either my accounts (but could do these retrospectively) or expenses. I paid for some things in cash so these won’t be accurate. Thanks again.