This website is vulnerable to POODLE (https://www.ssllabs.com/ssltest/analyze.html?d=historiapojazdu.gov.pl) and https://blog.mozilla.org/security/2014/10/14/the-poodle-attack-and-the-end-of-ssl-3-0/

The website needs to update their certs, there is nothing you can do from your end to change their security.

But can I access that website without improving their security?

No, because accessing that website is extremely dangerous to your computer's security. There may be other browsers that allow you to visit that page, but that number will rapidly shrink.

If you read the links I gave you, you'll understand what's happening here.

I understand whats happening, but my question is about accessing that webpage (whats important it's government website in .gov.pl domain name; also what you mean by being dangerous to my computer security, if it's static webpage when i am not entering any confidential/personal information?). So I understand that answer is No - there is no option to whitelist site or temporary disable this protection in Firefox