Hi newbie, (I'm sure you have a real name?)

Easy way to do this is to set the homepage node as a separate variable, then we can re-use it within the xsl:for-each loop...

<xsl:variable name="homepage" select="$currentPage/ancestor-or-self::*[@level = $level]" />
<ul>
    <xsl:for-each select="$homepage | $homepage/*[@isDoc]">
        <li>
            <a href="{umbraco.library:NiceUrl(@id)}">
                <xsl:value-of select="sectionNavigation"/>
            </a>
        </li>
    </xsl:for-each>
</ul>

Inside the xsl:for-each's select, we are using a pipe symbol to combine the node-sets.  So this would give you the homepage, then all the child nodes of the homepage.  (I removed the "umbracoNaviHide" stuff, as I assumed since you set the condition to "2", that you weren't using it anyway).

Any questions, let me know.

Cheers, Lee.