Hi Life are odd in that they call different products different names depending on which outlet is selling them! I think the hi life essentials are mainly an Asda thing, although a few years ago they stopped selling the pouches and Morrisons started selling them. More of the cheap shops - Wilkinsons, Quality Save etc. - seem to sell the hi life essential pouches. I am sure the petit pate tins are the same as the hi life essential tins. Asda sell the tins singly but they put out a mixed tray of flavours - they do turkey and giblets, salmon and a tuna one. Most in each tray seem to be the turkey one and that is Mosi's favourite. I did once buy a box of petit pate tins at the same time and they did a different selection of flavours, but I compared ingredients for the turkey and giblets one. Both looked the same visually, had the same list of ingredients (in the same order) and the same nutritional composition. I was convinced they were the same product. So maybe if I try to remember which stores sell the boxes of petit pate tins, I will find that works out cheaper than buying the tins singly.
ETA - the tins are cheaper on the hi life website but the trouble with buying mail order is postage (I didn't notice P&P?) plus I won't be in for delivery so will probably have a hassle collecting them. If I have to drive to parcelforce depot I will spend more on petrol than I will save buying online. Plus I don't have a debit card so have to use my pre pay credit card when buying online and there is a fee for using that. So not always worthwhile buying online.