Home page stuck in a perpetual re-direct to itself

I’m developing a new wordpress site in the same webspace as an existing site and hope to go live shortly. My home page to my development site is at the following URL: https://www.goldenageproject.org.uk/blog09/wordpress

Everything was working fine until I suddenly couldn’t access the home page. ie by typing in the address in the browser or clicking on the ‘visit site’ button with the dashboard. someone suggested that there cCould there be something in the config or http headers which would cause this. The index.php page seems to redirect to index.php, hence eventually it times out as it cannot complete the request.

Can anyone help me? I’m not that savvy with looking at .php.