Trust me that this is how you get what you're after without worry. I just did one this week. It will give you pink and deliciously juicy, but not overly rare as you said. I shudder at the idea of well done leg of lamb, I wouldn't mind stewing other cuts like that, but not the leg.
You will need a thermometer. That is the best way, rather than going on time. Then if you take it out at the exact temperature, and let it sit, and it will "re-absorb" its juices and continue to finish on the counter. You will get the perfect amount of doneness without stress that you'll ruin it for your dinner party. I recommend the thermometer that has a probe on a string and a unit that reads outside the oven. They're about $20-25, they can be set to alert you when it's reached the temperature you're after. (or you can use whatever thermometer you have).
For a really simple "Provencal" type of preparation, what I do is first rub the lamb leg exterior with a rub of a little, not too much, olive oil, and then a healthy amount of rosemary and thyme (more rosemary than thyme, or you can use just rosemary), and some nice grey sea salt (a decent amount, but not oversalted). Then I like to "stud" it with garlic, by taking a tip of a good paring knife, making little nicks in the leg, and pressing garlic slivers into that nick (quite deeply so most of the garlic sliver is submerged). Then I grind pepper all over it, I personally like a mix that is pink peppercorns mixed with black peppercorns, but whatever pepper you've got.
Then to roast, you roast it on a rack, uncovered, until the internal temperature measures 125 Fahrenheit. Then take out of the oven, cover loosely with foil (I put it on a warmed platter, but you can leave it in the rack and pan too), and let rest for 15 minutes minimum before serving. I think that temperature will really work for you. I like to roast it at a high oven temp, say 425 or 450 with convection, or 450 without, to get the outer surface to brown a little. Or start it high and reduce to 350, but usually I find I just keep it up that high and take out when internal temperature is reached.
You will also hopefully have a little jus in the bottom of the pan, pour off after it's rested.