"would you buy a refurbished one from Tesco direct,"
I wouldn't, but then I don't want the phone. Red the ad carefully, so you're aware of what you would be getting and then if you're happy buy it. Just don't expect to be impressed by its performance, because you won't be.
For just another £20 or so you could have the Motorola Moto E 2nd Gen phone that I told you about on page 1. I can't understand why you are spending so much time looking for the cheapest phone you can find when you can have something that's a really worthwhile bargain.