Align page navigation with header image

#access ul {
    display: table;
    margin: 0 auto;
}

don’t edit the theme Twenty Eleven directly; consider to create a child theme or use a custom CSS plugin.

align my page navigation buttons with my header image?

do you mean to center the menu?
try to add this CSS:

#access { text-align: center; }
#access div { display: inline-block; margin: 0; }

Sorry I should have been clearer – I would like the Home button to be vertically aligned with the left of the header image and the ‘Welcome..’ below..

Will try and create a child theme tomorrow when I can figure it out! Thanks!

But the header image resizes on different screens?

Ah so it does!
But surely you can have it aligned when in full screen?

As an example see https://www.fishpattie.com

The home button here is always aligned with Home in main text, regardless of window size..

So is that what you want, rather than the header image?

I would like my Home button to be vertically aligned with the left of my main text (So in line with ‘Welcome…’) when in full screen, yes

@media screen and (min-width: 800px) {
    #access div {
        margin-left: 13.5em;
    }
}

Awesome child theme set up using plugin called ‘Child Theme Wizard’ and success on the change!

Thanks very much Andrew!