Dover Calais ferries
I am contemplating a holiday in the UK in August. I am thinking of going via a ferry from Calais to Dover. However, I am wondering if it is best to book a ferry in advance online or whether you can just show up on the day and take a ferry. The same goes for going back Will it be cheaper to book online for example?
Also, the reason I ask is normally I would book online in advance, however I am going to rent a car and I don't know what dimensions it will be, so for that reason I can not book a long time in advance
TIA for all answers