1/. Identify your vehicle of choice. My advice is view a few.
2/. HPI it, and get it fully checked out. Inspection, service history, etc.
3/. Transfer/extend insurance. All you need for the ferry is a ticket to cover the size of vehicle you are driving.
4/. Paperwork is simple. Make sure transfer of ownership form is filled out properly, and that cert. of permanent export is sent off.
5/. Pay VRT the day after import. Put plates on, tax it and your away.