Hi caretodiffer,
To qualify you had to spend either £50 or £100 in one go excluding p&p between April 21st and April 26th. Relevant T&C below;
"6. To qualify for a £5 Account Credit you must order goods to the value of at least £50 (fifty pounds sterling) excluding postage & packing, to qualify for a £10 Account Credit you must order goods to the value of at least £100 (one hundred pounds sterling) excluding postage & packing, between the hours of 21:00 BST Friday 26th April 2013 and 20:59 BST Monday 29thApril 2013 with Ideal World and of 08:00 BST Friday 26th April 2013 and 23:59 BST Monday 29th April 2013 with Create and Craft. Orders may be placed on the telephone or on the websites
www.Ideal World.tv or www.createandcraft.tv."
Below is the actual page address of the T's&C's for this.
http://www.createandcraft.tv/5-and-10-Account-Credit-Apr-2013.aspx
Hope that helps.
Jen