Temp Index page while I develop Theme?

Hello,

I would like to know how I can have a tempory index.html document displayed while developing my theme behind it.

I know that index.html overrides index.php but if I do this I can’t actually see the site as I work on it. If you click preview post or page it just takes me to index.html

Can anyone help me out here please, it must be a really common issue.

Many thanks