Thyroid UK has two web adresses, thyroiduk.org and thyroiduk.org.uk
Both adresses should go to the same place. But as of Sunday morning (9/7/2017), thyroiduk.org is working properly. However, thyroiduk.org.uk is still having problems.
So please go to thyroiduk.org (make sure that .uk is omitted at the end)
If you have reached the correct place, it will look like the picture in this post.
Hopefully it will get sorted on Monday and it won't matter which one you go to.
The Health Unlocked site forum suddenly disappeared when I was tying.
My PC said it was because the security certificate for the site had expired at 1pm Sunday 1 July. A few hours later it was working again.
Yes, this forum fell offline for a couple of hours while they sorted out the issue. Certificate has a new expiry date now 
For clarification, this post that you're commenting on was not about the forum, but about the main Thyroid UK website here thyroiduk.org (Thyroid UK is the charity that runs this forum here on the HealthUnlocked platform.)
