Hull to Zeebrugge/Rotterdam ferry seems very expensive

[stub101]

I am planning a bit of a roadtrip for early July in the TVR from Leeds to Italy and have been trying (without luck) to find a reasonable price for a ferry to the continent from Hull! I beleive the only route is Hull to Zeebrugge/Rotterdam and this will also allow me to take in the TVR meet at Zolder in Belgium.

Does anyone have any tips of finding cheap fares for one person and one car because I have tried a variety of different dates at the end of June/July and cant seem to find anything for less than £400 which sems extortionate to me! I have read/heard many stories of people getting cheap crossings for ~£100 but I cant find anything close (and need to save as much £££ for petrol as my trip is about 2600 miles!)

Separate to this I have the eurotunnel booked at the end of August for my trip to Spa for the Belgian GP but wanted to do things a little differently this time with so many more miles ahead.

Any help much appreciated.