Tesco Gabalfa is my 'big shop' store, and I always use the manned heck-outs if I can. I don't really mind using the self-check tills, but I find them so bloody irritating - they seem to stop working for the slightest thing. If you move the shopping around, it flashes red. If you try to adjust the contents of your bag, it flashes red. Buying ber? it flashes red. You get the picture. I've yet to get through once, without it going off.