...I think!

Firstrly, it just so happened that my home page (bbc.co.uk) was in a blocked range: because of this I thought that my entire web access was blocked.

I found the following quote on the Phoenix Labs FAQ page:
"Is it safe to turn off the “Block HTTP” option?

It is recommended that you add it to your pemanent allow list instead. If Block HTTP is off, it is possible for others to sneak in through port 80 or 443."

So I have blocked HTTP again and allowed the BBC website and all seems to be fine.