Hello there @Salbeer !
SW is brilliant for all different types of people including vegans! The plan consists of the following types of food: (1) Free foods: this includes fruit, veg, rice, pasta, beans and pulses etc all of which are vegan. It also includes eggs, lean meats and fish. Vegans can use tofu (am I correct regarding Quorn not being vegan? If it turns out that it is vegan that's free food too) (2) Healthy extra A: this is largely based on fixed amounts of cheese and milk. Vegans can instead enjoy rice milk or soya milk (check out this infographic: http://myweightlossdream.co.uk/slimming-world-healthy-extras/) (3) Healthy extra B: this is bread and cereals in fixed amounts many of which are also vegan (check the infographic on the same website) (4) Syns: these are treat foods or additional healthy extras: biscuits, cakes, nuts, alcohol (you don't need to worry about this one lol). Hence, it is very easy to be vegan and follow the SW plan! It's just tailoring the plan to fit around your dietary preferences!
Let me know if you need any more info! Also let me know what meat substitutes vegans eat and I'll find out whether they are free or not xx