I use a 150w inverter which plugs into the 12v socket to charge my laptop and shaver up, phones and watches are charged up with a USB adaptor which also plugs into the 12v socket. A 150w solar panel keeps the battery charged up.
We have a device from CPC, it up's the cars 12v via a selector switch, so 15v, 18v, 22v or 24v whatever your Laptop requires, the unit comes with a whole bunch of connectors to fit just about any laptop.
Very handy bit of kit, and I often use it at work when I am on site, of grid.
We charge the tablet using a power bank. Have also plugged it into the car when using it.
Have also on occasions asked at the reception where they charge phones/electrical items for free/a small charge/ a donation to their chosen charity - often air ambulance or other very useful charity.