I've used this as an alternate to Screwfix or Toolstation. Generally there tends to only be a few pence difference in prices so it's all down to convenience. I don't have a Tooled Up local to me so delivery costs are normally around £3.95 but sometimes this can be offset if Screwfix or Tooled Up doesn't have items in stock. Delivery is generally within about 5 working days as standard and items come well packaged.
I've rarely seen codes for here but I'm not subscribed to their newsletter but I'm sure they do exist, just probably not as frequent as Screwfix or Toolstation.
I've never had any issues with the quality of items received and not had any need to contact customer service.