Best practice for using brand domain, website page, landing page, blogs
I'm a little confused. Why would your company want to have two seperate domains, with two seperate blogs? Do they sell completely different products and will they have completely different content? I may not be understanding you correctly so a little bit of background information would help!
As @webdew mentioned you can just host the blogs on a sub domain or a subdirectory. However a subdirectory would be your best bet in terms of ranking and SEO. Because Google sees subdomains as a completely seperate entity that the parent domain. So any content and what not on the subdomain wont help the parent domains' SEO or domain authority.
To begin .com and .co.uk are called top-level domains, or TLDs. The only difference is .co.uk is country-specific or country code top-level domain. It attracts more regional traffic. You can find more information here: https://hostingdata.co.uk/com-vs-co-uk/. If you want international traffic, you should use .com.