Well, DD, DGD (18) and I are all vegetarian, and I could bore you rigid with suggestions. However:
We all agree, that if it is a roast dinner, what we love is to have Yorkshire pudding, and roast potatoes and vegetables - bung in cauliflower cheese and that is us sorted. But potatoes cooked in oil, please. I have a recipe for a "mushroom roast" which everyone loves, and which goes down well with chicken type roasts.
We also, sometimes, put lots of chopped and cooked mushrooms and garlic into the Yorkshire pudding mix, which serves us nicely as a main component. You can do similar things with Anna potatoes.
Spinach or parsnip roulade is good; blue cheese savoury cheesecake; homity pie (love that!) and, of course, the endless variations of vegetables in pastry that turn up on most vegetarian menus, anything from something akin to a Cornish pastie to mushroom Wellington.
If all else fails - go to M&S!
Sorry - said I wouldn't bore you...pm me for recipes if you like.