Can I add a barcode to the submission/thank you page etc?

I know .... another ridiculous question ... but if anyone has any insights please

Hello northview99,

Yes you can add barcode to your form and thank you page. Firstly https://www.jotform.com/help/211-Setting-up-the-Thank-You-Page here you can find how can you edit your thank you page. If you have got your barcode as an image just add it. If you don't have, no problem :

You can add https://www.jotform.com/widgets/qr-code qr code / barcode to your form with this widget. Then in thank you page editing area clicking with "form fields" you can select the qr code and add your thank you page.

Regards, Metin