Hello there. Sounds like this is a knock-on effect of us testing the new site earlier this week. Apologies for the inconvenience. If clearing cookies didn't work, would you mind trying a different browser or using incognito mode and seeing if that works?
This is just a temporary issue that will hopefully be sorted when we move to the new site, so thanks for your patience.

Hi OP

This may be a knock on effect from the new site launch.
Can you try clearing your Mumsnet cookies? It worked for me when I was having issues yesterday!