No, especially for someone with sensitive skin and no DIY experience, I would not call it easy. Starting from blonde definitely makes the process easier since you need to be incredibly light for silver and grey tones, but there's also toning issues to deal with when you want an icy, yellow-free result that might be a lot for a newb. Anything that lightens will be permanent, even after the grey fades you'll have lighter hair, and you'll have to lighten for grey unless your hair is already near white. So easy for a pro, and easy for a very experienced DIYer, but not easy for your first attempt.
You're already going to need to be careful if you've got extremely sensitive skin, as hair bleach is not gentle and while you don't want to smoosh it into your scalp some will always get on your skin. If it turns out you can't stand bleach you'll be grateful for the giant salon sink that gets it off your scalp quickly, and a pro can help you fix the color if bleaching turns out not to be an option.