I've been veggie for years so cook a lot of beans, curries, middle eastern stuff. A lot of pasta dishes are veggie so easy for newbies. But there is a place for veggie fast food, varying food sources/textures.
Don't know about Tesco's but Sainsbury's and Waitrose both do good ranges, Higgidy Pies are pretty tasty, but overpriced; Tivall do a good range of soy 'meat' balls - great simmered in a tomato sauce and served with pasta and grated cheese - also good burgers, great hot dogs and their mince doesn't clump like Quorn. All cook from frozen very fast.
Tofu comes in a wide range now, the basic stuff good for stir-fries, but hard to store, the smoked kind easier to work with and tastes better. There's a variety that's flavoured with basil and firm so slices well, good in sandwiches and in salads. Halloumi cheese, slice it and then cook on a griddle or lightly-oiled pan, great in salads and in wraps just use the tortilla wraps; also good in wraps are falafels, particularly with hummus, salad and a dash of sweet chili sauce.
Holland and Barratt are good for veggie sandwich fillings like veggie bacon, veggie slices and so on...
Agree with other posters avoid Linda McCartney all taste vile or bland. But standard veggie sausages have improved and work well in all normal sausage-related meals, the spicy ones tend to be nicest, but do need to coat with oil before cooking, or very dry. M an S also has good posher veggie ranges, especially towards Christmas. Also a lot of Indian and Chinese food ranges are okay, just check the label, will have a suitable for veggies label somewhere or the V sign!