We've just received confirmation that Orange UK is rolling out the Windows Phone 8107 update (for the Lumia 800 anyway). The update addresses the pesky disappearing keyboard bug among other issues. Should you be on the network, and are waiting for the notification, be sure to regularly check Zune when plugged in.
Let us know in the comments should you have the update on the carrier, or are still waiting.
Thanks James for the heads up!