Hi, I've been speaking to my host about it and here's the response from them:

"We checked the parse times on multiple sites on your hosting. All seem to be working well but then again most are running Gzip. However as soon as we switch this function on for your site (via admin>configuration) the front page of your site won’t load? – We haven’t seen this problem before so may be worth looking on the forum."

I've asked them to take another look and hopefully it'll be something simple