Can't really be accurate without knowing weights/measures but hopefully this will help...
Roast chicken (meat only) 4PP per 90g portion
Mashed potato (plain) 1PP per scoop/60g
Mashed potato with marg 2PP per scoop/60g
Potatoes roasted in oil/lard 4PP per 100g
Yorkshire pudding 1PP per individual (20g)
Sweetcorn 1PP per tblsp (30g)
Peas 2PP per serving (80g)
Other veg 0PP
Gravy powder/granules 1PP per tblsp (9g)
Doesn't matter that its not 100% accurate but it gives me a good idea.
Thanks, off to my mums now for Sunday roast, at least I know I can stay within my 29pp and not use any off the 49 extra and still have enough left for dinner