Argos have a the iPad 2 WiFi 32GB White instock at the moment for home delivery.
I know it's not the cheapest deal around, but it's instock (for the time being).
Saturday delivery is the earliest delivery slot (free).
Enter your postcode & click 'check stock' - it should be available for home delivery.
I have just placed my order so I can confirm this is working.
My delivery: Saturday 2nd April 2011 7:00 am - 6:00 pm :)