If you are going to get any livery on the vans, cheap is not always your best option. Cheap means lower end vinyl that WILL shrink and crack sometimes in as little as 12 months. Fleabay sellers will cut and send prepared vinyl without worrying too much about longevity, beacuse once its gone wrong, they have the nice feedback and your money.
Digital print has a life span of 3-5 years and MUST be laminated for any kind of durability. Any good sign maker will advise you accordingly depending on the layout you want and should be able to tweak & produce designs that work with what you want. Less is more, in as much that too much text looses its readability quickly.
Font choice - beware of windows fonts that look good on screen and paper when at size 12. Once blown up to 150mm text you start to see the low quality of the finished article. Many have a series of short lines to form curves, some are littered with other errors. A pro font may cost £25, but its worth it for a £150 berlingo of £220 transit (average price for livery)