Does anyone know a cheap way to get ferry tickets from the UK to northern Ireland ? And a cheap place to hire a small van?

I would advise looking at all of the ferry promotion companies for the specific routes to Northern Ireland that you are interested in. Do you know the ferry companies that run the particular route? Once you know, checking their websites for promotions is probably your best bet. Regarding the van, it is best to find a list of your local van companies and give them a ring for cheap prices for the time when you will need it.

Hi radish, and welcome to the forum.

TheBandit's right, just google 'cheap ferry tickets from UK to NI' and a list of ferry company sites will come up. :-)