GFB and BB are somewhat undesirable for polearm wielders as you can only use such at 5 feet, while as a PAM you want to keep the bad guys at 10 feet. Further I wouldn't want to go against any undead or lycans with a -1 inititative and being surprisable. Those creatures are meant for ambushes, especiallly in dark enviroments. Another problem for humans, which have no darkvision.
Under these conditions you needn't have a lot of bad luck in order for the monsters to act in two full turns (surprise round + higher initiative) before you can do anything and those might be two turns too much. Thankfully as a pally you become immune to diseases and poisons, but some undead have effects that you are not immune to. Not to mention any damage they might be dealing in two turns.
If you do not want to keep it that way I suggest you pick up the Alert feat asap and thereafter the Sentinel feat. Yes, no ASI then, but the first will be quite essential tactical wise, while the latter is more than useful for a polearm wielder, since you can prevent some nasty folks from coming into reach, so they lose a whole turn of attacks.
Having no shield means you start with a chain mail or AC 16, which is neither bad nor really good. Make sure you always have holy water at your disposal, because Protection from Evil and Good will most propably become your best friend in such a campaign.
The other method would be a Dex/Cha build among another set of weapons and feats, maybe even another race.
You needn't worry too much about concentration because with Con 14 and Cha 16 at lvl 6 (aura) you will only have to roll a 5 most of the time (DC 10) to maintain concentration. Only if you take 22 damage or more with one blow things will get more complicated.
Or start as a fighter. You get prof in Con saves out of the box, a second lvl later on will give you a second fighting style (GWF and Defense will be your best bet), an action surge 1/rest, and you still got 8 lvls of pally to go for. Or get 4 lvls of fighter and grab the Battle Master subclass for some nice maneuvers and superiority dice.
Now with you having greatsword +2 in mind, you might take the alert feat right away at first lvl. But as long as your DM is somewhat 'pro-party' he can simply transform the greatsword into a halberd+2...unless AL rules forbid this action (Haven't read the rules completely, sry). Otherwise pick up the greatsword and get Alert, +2 Str and GWM along the way.
On a sidenote, I guess the best, but non-choosable paladin subclass for this campaign might be the Oathbreaker (*mean grin*)
