I always do roast potatoes and roast sweet potatoes. The sweet pots don't need par boiling first. Just toss both in a little olive oil before popping in the oven (180 C for 45 mins to 1 hr). Usually have carrots and brocolli and instant gravy from a packet (shock horror, not the sort in a jar, I'm hopeless at making it). Some redcurrant jelly is nice too. Oh and a glass of wine. Hope it goes well.
Don't forget the parsnips!!....I do mine in a pan: peel and cut into wedges,par-boil first,pop into a frying pan with a splash of oil and cook until starting to colour...then sprinkle over some dark brown or muscavado sugar,continue cooking until edges are nicely crispy...yum
When doing roast potatoes, its nice to part boil them them put them in the roasting dish and slice up an onion and wedge in between your potatoes and drizzle with oil, gives a lovely flavour to the potatoes...delicious!