Yoghurts, smooth low sugar ones. The small muller light smooth are good.
Soups, small low fat/sugar ones. The weight watchers range are good. cup a soups not so good. You can go for the fresh ones like covent garden etc but you will need to blitz them smooth in a blender first. Aim for less than 5g sugar and fat per 100g.
Milk - preferably skimmed but semi is ok.
Fruit juice - pure orange is a good source of vits
Sugar free squashes - you'll need to keep your fluids up post op and having a good variety in helps
Sugar free ice lollies - jubblies or the tube ones, the ones you buy off the shelf and freeze yourself.
Low sugar probiotic drinks - good for rebuilding your inner bacteria after the op, will help with your bowels.
Benefibre - the powder of the gods, helps restore bowels
Mostly in the early days its soups, so its good to have a variety of flavours, and get a hand blender or something similar.
HTH
Shel x