We delivered ours from Fareham to Brighton when we bought her without replacing the standing rigging. At that stage the rigging was c.18 years old. The insurance company was aware and said that they would not cover us if there was a failure during the voyage. It was early May and the wind was very light so we motorsailed all the way. Therefore there was little strain on the rigging.
If the insurance company will play ball and you are prepared to take the risk it would be possible to sail or motor given the right weather window. In my experience, getting thrown about by the swell in Brighton Marina entrance is likely to put the biggest strain on the rigging!