So, I have a level 19 Fighter that uses a polearm, basically the build you are looking for, been playing him for a year and he is very good but I have learned a lot over the time with him. I'll try to be concise.
The feats I have; Polearm Master, Healer, Magic initiate, Great weapon Master, Sentinel, Heavy armor master, and defensive duelist.
First off, don't neglect your Con. My biggest regret is that +2 con that is still staring at me, at this point it means that it is very difficult for me to stay in the front lines for long without going down and I need to be very careful where and how I attack, I've even started using a sword and shield when I think the group needs more defense because I just get hit a ton.
Secondly, Sentinel is overrated. I very rarely get to use all or even part of that feat in a fight, when I do it's nice but usually it's a waste.
Great Weapon Master is also very overrated. If the fight is going to be tough you are better off not using the -5+10, and the random bonus action is only a 3 average damage boost. Definitely not worth it.
Battlemaster is definitely the way to go. You have more options of who to hit generally and having great tricks to use with them is incredible. Throwing a d8/10/12 on a crit is also just awesome for your dpr(you decide to maneuver after you roll) I would definitely advocate the feat to give you more dice/maneuvers. Trip, Menacing, Commander's, Pushing, Riposte and Goading are all extremely useful.
For races, I went human but anything can work honestly, Goliath would be my pick if I could re-do, more defense and better offense always helps.
Some things to remember; Unless you prioritize con hard and get Defensive instead of GWF you are not a tank, you cannot take on all the damage, don't act like it. This just isn't a defensive build so bear that in mind. You also need to remember that you don't get an opportunity attack until they get 10' away from you, keep that in mind with your positioning. You don't have very good ranged or aoe abilities. Basically you have very good single-target damage and some combat tricks but you are very limited in your variety. This can be good or bad.
Ways to shore up your weaknesses;
-Multiclassing into Barbarian.
--2 Levels gets you 2 rages, reckless attacks and danger sense. Great value for survivability and offense. I did this and it has definitely payed off.
-Mc'ing into Ranger.
--Horde Breaker, Hunter's mark, Ensnaring Strike, Absorb Elements, all can help you deal with aoe and be more defensive/versatile.
--Downside is you have to worry about wis now.
-Mcing into Warlock
--Hex, the ice armor one, aoe cantrips and eldritch blast. 2 levels basically shore up most of your weaknesses plus if you go demon you get temp hp which is nice.
--Now you need a good cha(you can get inspiring leader if you do)
--This is the best option in my opinion now.
All in all this is a good build but not nearly as busted as it looks on paper.
<.< that wasn't concise at all, I would apologize but I'm never concise so meh.
