Ronk,
Never let anyone else decide the risk that you alone are prepared to take. The ferries may well run on your intended travel date, but you might not want to travel then because you don't want to expose yourself to an unacceptable perceived level of risk. In the greater scheme of your finances, losing a £100 deposit is no worse than getting a puncture and buying a new tyre. Don't give it a further thought.
Never let anyone else decide the risk that you alone are prepared to take. The ferries may well run on your intended travel date, but you might not want to travel then because you don't want to expose yourself to an unacceptable perceived level of risk. In the greater scheme of your finances, losing a £100 deposit is no worse than getting a puncture and buying a new tyre. Don't give it a further thought.