I have one of those that comes in a case, they tend to be a bit naff for proper typing.
You can use any USB (with a USB OTG cable) or bluetooth keyboard, I'd recommend some kind of stand to prop the Hudl up if you don't have one already. Despite what you may find on eBay there are no Hudl specific keyboards, they are all either USB or bluetooth. Tesco do not make a Hudl specific keyboard.
If space is a concern there are plenty of decent 'compact' keyboards, which feel like laptop keyboards.
http://www.amazon.co.uk/Anker®-Blue...75&sr=8-2&keywords=bluetooth+keyboard+android
Is an example. I personally use a USB keyboard when I need one.