In reply to r0b:
Terms and conditions may be written by the seller but they have to equally fair to both parties, otherwise a judge might determine that part or all of the contract is unenforceable.
Having just read UOG's Ts and Cs, they seem to be operating in a grey area of the law. They are taking money (so ought to be entering into a contract) but then saying the contract is entered only when they send the goods. This seems to be an instance where contract law hasn't kept pace with the digital age.