Mrs B normally uses an iPad, but she recently bought herself a Refurbished HP Probook 14" for £199 from Amazon, I went through it with a fine toothed comb when it arrived, you would not have known it was refurbished, looked brand new and so far has given great service.
I would agree with the essence of the answers above. I have two second hand laptops in use, one i7 and the other i5, both are Dell e6420. The former has a camera, the other not, both have a DVD drive and both have an SD slot. They do all I want and can no doubt do more besides. Each cost me well under £100 on eBay but you regularly get them for around £130-150 provided you are prepared to accept some blemishes. They, particularly the i7, got good reviews at the time they were launched.
Mrs B used Amazon, Look for (Renewed) in the product description.
Click on the item and they will tell you who is selling them, then you can contact the seller and ask whatever you like, that's what she did.
stick with an intel i5 3rd generation cpu or higher, 4 or 8 gig ram
and ssd drive would speed things up as well, you could put one in yourself and install windows, or buy a lptop with one already.
AOG, regarding your safety concern, I employ a simple/simplifying approach: I use a bootable portable drive. This allows me to use any computer that I can boot up from scratch, safely and with access to all my data no matter where I am. Also, I of course have no need to establish or work around a new/unfamiliar operating system.