there are the chassis/engine rails/legs, suspension towers for starters if either of theses are broken/bent etc then a garage will nedd to look at it. other bits include the front crossmember slam panel thing but this is easily replacable. you best bet is to strip everything off take a good look and see exactly what is goin on. it isnt hard to get the wings/bumpers/crossmember/etc off just bolts to undo and loads of sealant to cut away but you are lucky cos none of the panels should be welded on. hope it isnt serious!