Eire, Ive just looked into getting some whey protein mix, which would be suitable for vegetarians (not vegans though as its milk protein). Its a high quality protein mix, that has minimal carbs and just 98 cals for a scoop. I orderded mine yesterday so havnt received it yet but it sounds like the sort of thing that could help you along your way. It is probably very similar to the Target Slim shakes, but less than 2 carbs a portion, and mixes with 250ml water. Ive ordered the Mint Choc flavour, the reviewers on the site (myprotein.com, True Whey) really love the mint choc.
It would give you the extra protein you need to stop you getting hungry, whilst keeping the calorie and carb consumption down.
Exante is a meal replacement that i use, and its way cheaper than all the other replacements. £100 for a months total supply (dont know what that compares to euros, maybe 120?). Ive no idea how that compares to Target Slim price wise. In a mixed bumper pack you get Shakes Soups and Bars, 1 of the soups would not be suitable for you as its chicken flavour (somehow i doubt there is any actual chicken involved lol) but there is just 7 of those in the whole pack of 84 items, but eveything else should be ok for you. You can also buy a bumper pack of just shakes, which are chocolate strawberry banana and vanilla flavours. If cost is a consideration it might be worth looking into.