Livre d'Or

Laptops: because 'downgrading' (ha!) to Windows 7 is very, very widely available, your main issue is going to be the screen, I think. You want something with lots of pixels, or Photoshop is going to be a pain. Lots of pixels on a laptop costs £££s in a way that they don't on a monitor or tablet.

If you are not going to do work in transit, the consider getting another screen / keyboard / mouse, and have something that is very portable. Think something down to Mac Mini but as a PC: there are more on the market now. See this as one example.

Or just have a desktop in each location and sync them online. I was surprised at how little capable desktops can cost now.