There's no cooling-off period for items purchased (or ordered) in a shop. The only exception might be where a store clearly advertises a policy such as "You can return unused goods within 30 days for a full refund". (Under such circumstances it could be argued that the statement formed part of the contract of purchase). Since your daughter was not relying on such a statement when she placed her order, she has entered into a legally binding contract to purchase the bed.
The absence of the leaflet might actually place your daughter in a worse position than if it had actually been provided. If the leaflet had offered the chance to cancel the contract within a certain period, your daughter could argue that the statement formed part of the contract which she'd entered into. However since she signed the contract without any knowledge of such a discretionary term, she's left in the same position as anyone else who buys in a shop(where no additional rights, in respect of cancellation, are offered by the vendor). i.e. there's NO cooling-off period and she's stuck with the contract.