You can't evaluate page load times from the perspective of including the (javascript/CSS/AJAX-based) UI rendering (not simply fetching of files over HTTP). That requires Selenium.
To add that to jmeter load tests, you do either of the following:
- run a selenium script separately while jmeter script is running
- run the selenium script code in jmeter as a separate single thread using the WebDriver plugin for jmeter
in either case, this is only useful if you convert selenium scripts to jmeter in the form of translating navigation between pages into HTTP requests with jmeter. If you just blindly convert by putting in selenium code to jmeter via WebDriver plugin and multiple threads for that, you gain no real benefit.