Just had roast beef with mashed potatoes. Not too good; no one in my family seems capable of cooking good roast beef. Oh well, it's filling and I don't notice now.
It's not that difficult, try this. Sear it to seal it - hot pan; transfer to dish and put into a hot oven (200-220C) for half an hour per pound of weight and maybe a few minutes extra; personally, I like my meat reddish-pink in the centre, so I tend to go for rarer roast beef, it gives a better flavour, I feel. Remove from oven, and cover with tin foil (retains heat) and then let "rest" for 15-20 minutes. This makes it both easier to cut and preserves flavour. If you want gravy with it, pour some of the juices off, add perhaps salt and pepper, a small glass of red wine and some flour, stirring. Heat until reduced by half. Serve with the roast potatoes (I gave a recipe a few posts back), or plain boiled potatoes, or gratin dauphinoise potatoes (par-boil potatoes, drain, place into deepish dish along with several cloves of crushed/minced garlic, double cream, single cream and milk - just almost cover the potatoes - and cook in a hot oven for 35-45 minutes). Serve with tossed greens and some red wine. Eat and enjoy.
Cheers