Book as far as in advance as possible.Last minute deals are rare on ferries, so don't be hoping prices will fall, they are more likely to rise. This is really important on overnight sailings that require a cabin – The cheapest cabins tend to sell out the quickest.
Do ferry prices change?
Pricing. Firstly, freight ferry ticket prices are generally fixed for the whole year, and do not suffer from seasonal fluctuations. This means that the prices will be the same all year round, regardless of when you need to travel.
Do ferry prices go up?
are they like uk train or aeroplane fares, likely to go up, or are they standard prices that will remain the same up until the day I travel? No – ferry prices are fixed. Like Anninhk says, prices are fixed. Unless there is a new law that taxes go up, they don't change over the year.