I am torn between an ipad 3 or a mini. I quite fancy the mini with 3g but from what I have been told it seems that it takes a nano sim and these aren't yet available (I know the 3g versions aren't either but will be soon?). Anyone know anything about this?

Surely the sims must be available as the iPhone 5 uses them

Don't know what to mean by "3G versions". 3 currently only have 3G nano Sims as well as micro Sims.
Have you not looked at the 3 sim only page on their site?
Nanos are available. See here http://store.three.co.uk/SIM_Only/Mobile_Broadband

I think the OP meant that the 3G iPad mini isn't available yet.

But yeah, plenty of nano-SIMs already available.

Thanks. Obviously wasn't looking in the right place! I had a look at Vodafone as they do one for the bigger ipad which costs £5 for 250mb and you just top it up as and when you want - no contract of any sort, which would suit me. They didn't seem to have a nano sim at all for anything. Will have a look at 3 etc, and yes, I did mean that the mini 3g version isn't out yet but I believe it will be soon.
Cheers!