If it were my choice, I would bite the bullet and go for the Apple reconditioned offering. You won't save much, but the Apple reconditioned machine comes with the same warranty as a new from the factory Mac, and as Artie mentioned it is eligible for Apple Care which in my experience has proven to be worth a LOT. (On multiple occasions Apple has presented me with a new computer or device thanks to Apple Care.) Based on your description of how the machine is used, I would look for savings by buying Apple's price leader offering, a MacBook Air, with minimum memory and storage capacity. Good machine, and more than adequate for the described task, but no 21" screen 😢.
Another alternative in just over the Macfinder dot co dot uk price would be brand a shiny new iPad together with a Smart Keyboard. A smaller screen, but dead simple to use without some of the complexity of a Mac, albeit at the expense of a smaller screen. However, the screen is good enough that even my 82 year old eyes find it more than adequate for internet browsing and mail, not to mention drawing, graphics, accounting, database operations, writing letters, etc. It is what I recommend to most friends my age.
If that is still too pricey, AND Macfinder dot co dot uk has good customer ratings, the prices are in the right range. | 
