I got this on the end of an order confirmation e-mail from OcUK in Feb '06 - They don't seem to include it anymore, but it says you have to pay for postage if you just don't want it.
Distance Selling Regulations (2000): You have the right to cancel the contract relating to your order at any time up to the end of 7 working days after the goods are delivered. To exercise your right of cancellation, you must give written notice to Overclockers UK by letter, fax or WebNote giving details of the goods ordered and date received. Notification by phone is not acceptable. If you exercise your right of cancellation after the goods have been delivered to you, you will be responsible for returning the goods to Overclockers UK at your own cost. You must also take reasonable care of the goods. Returned items must be packaged properly and shipped in a plain outer box. Please try to include all internal packaging, cables, manuals, drivers and protective bags, however small. Overclockers UK cannot take responsibility for goods that are damaged or lost whilst being returned.
Overclockers UK will refund you within 30 days for any sum that has been paid by you or debited from your credit or debit card for the goods. If you do not return the goods as required, Overclockers UK may charge you a sum not exceeding the direct costs of recovering the goods. The goods must be returned to Overclockers UK (Esnet Ltd), Unit 40 Imex Business Park, Ormonde Street, Fenton, Stoke-on-Trent ST4 3NP.
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Exceptions to Distance Selling Regulations (2000): You do not have the right to cancel the contract under the Distance Selling Act if you have collected goods or ifthe order is for computer software which has been unsealed, or if you are not a consumer i.e. a company, partnership, sole trader or any other commercial body or registered charity.