do you need to tell them if you have a tow bar mounted bike carrier ?

I think they would view it as a trailer ? so need to pay extra .

anyone has any experience on this ?

ferries like to know and IIRC have a drop down box on website

tunnel dont care

used both with tow bar racks many times

There is normally a maximum length allowed for a standard car, as long as you are less than this – you should be – then you are fine.

thanks , it is a Zafira, and the rack is a 4 bike , so might be too long .

Depends which ferry. If you go out from Hull and back via Dover ferries don’t care but as it recall if you Dover it both ways they do.

Current Mondeo with three bike rack, so very long.