I took a set of steps on holidays so I could access the roofbox and tie on the surfboard etc! (Now on the look out for a short, light step ladder for future trips!)This works for washing the roof of the van at home:
Not so good for getting access to roof rails etc when you're away.Werner Fibreglass 1.7m 6 Step Swingback A Frame Step Ladder - Screwfix
Order online at Screwfix.com. Moulded brace and foot pad provide bracing strength and help prevent rail damage. Non-conductive stiles, slip-resistant steps, large platform and multi-functional holster top for stowing tools. FREE next day delivery available, free collection in 1 minute.www.screwfix.com