You're spreading your stats pretty thinly between CHA (Face), STR (Grappler), DEX (Rogue MC Requirement), and CON (Grappler).

Do you really need the level in Rogue?

You already have Hex to put your opponent at Disadvantage in contested Athletics checks. Is Expertise[Athletics] really worth the investment?

I'd just go Warlock(5)/Battlemaster(3). Heavy Armor proficiency, STR/CON saving throw proficiencies, and Defense Fighting Style will make you very difficult to hit, and Armor of Agathys will punish those who insist on attacking you. Add in the Blade Ward cantrip, the Parry maneuver, and Heavy Armor Mastery to keep those Agathys Temporary HPs around for absurd lengths of time.

Your initial decision to put five levels into Warlock implies that you're more interested in your "Face" and "Caster" abilities than your combat duties, which is perfectly fine. Leveling up Warlock further will grant you more powerful Armor of Agathys, along with higher level invocations and spells.

Nevertheless, you will probably want Extra Attack at some point, since it allows multiple Grapple attempts per round (Or Grapple + Push-Prone on one turn). Battlemaster(6) is a good eventual goal because it gives you two ASI/Feat choices and Extra Attack.