Downsides to buying a van as a family vehicle

Hi All,

I'm after a van for as a family wagon, budget is below £30k. We're a family of five (3 kids - 7 and 5 year old twins) but want six seats (to take my dad with us on occasion). We do a lot of camping, walking at weekends, and I'm also a keen mountain-biker so want something I can stuff in and clean up more easily, and perhaps even to rough it in overnight. I'm also keen to try camping in France annually by taking the ferry or chunnel, so ticket prices are a consideration.

The van would replace the currently family car - a Seat Alhambra. The missus uses this for going to her part-time (local) jobs and ferrying the kids about, while I use my Civic to get to work and back. We could swap but it'd be a big increase in fuel costs.

I'm erring towards a Transit Custom as I'm not keen on paying more for an older Transporter and I intend to keep it for a long time so not bothered about the depreciation. Neither am i scared of the wet belt or intending to ever convert it to a camper (not for a long time at least). Although the bulkhead in the Transit reduces flexibility but it does separate the load. I also can't decide between SWB and LWB. LWB offers more room but more difficult to manoeuvre (marginally).

I'm not a tradesman so it'll never be used for work. As far as I can understand they're all classed as N1 rather than M1 so would be subject to lower speed limits - does anyone every pay attention to this? I know I'd have to pay VAT if not paid already. Are there any other downsides I need to consider?

I don't mind going for the minibus versions (Tourneo Custom or Shuttle), which aren't subject to lower speed limits but understand tax is higher? Are there any other benefits of having an M1 class vehicle (differences in ferry charges for example)? I'm happy to take the 3rd row of seats out and store in the garage.

Chucking it out there for your thoughts, what would you go for if you were me?