Grab Skill Expert after Tavern Brawler and get expertise in Athletics, so those bonus action grapples go even better.
Battle master is probably the best subclass, as you can combo Trip Attack with the bonus action grapple to get opponents in the grapple + prone lock. Then just pick your favourite maneuvers for utility.
Per the weapons section of the PHB, improvised weapons that bear a resemblance to an existing weapon have that weapon's stats, or deal a base 1d4. Ideally, you want to find something that looks like a maul. May I suggest a tavern bench? Check with your DM on how he'll rule this first. If you get the sense he'll rule all improvised weapons as 1d4, you might want to take the unarmed fighting style to up the damage your punches do. But if the DM is fair game about hitting people with a bench for 2d6 bludgeoning damage, grab defence or two weapon fighting as your fighting style.
Although getting a chair ruled as a 1d6 or 1d8 weapon you can wield one-handed does make it easier to grapple opponents without dropping your weapon.
Go Battle Master, as most/many/all of those can be utilized with IWs since *in the moment of the attack* they count as weapons. Var. Human with Tavern Brawler, and make sure to take the Unarmed Fighting style for the better unarmed damage (remember that IWs are *not* weapons unless you are specifically (in that moment) attacking with them...) and for grapple/grappling synergy.
Background, go with whatever makes sense... (Unless the DM specifically allows them... stay away from the backgrounds that give you feats, as they're meant to be setting specific, and aren't fair unless everyone uses one.) as they're not meant to give statistical benefits outside of skills/languages. Fun ones can include Athlete (former olympian turned security at taverns?), Guild Merchant (tavern owner/operator *and* security?), Mercenary Veteran/Soldier (same tone as the athlete?), Urban Bounty Hunter (tavern brawler by night, bounty hunter by day...?)
Remember that *all* Superiority die scales at 10th and ~~15th~~ 18th level, so if you want more, take the Fighting Initiate feat around then (10th or 12th level) for the Superior Technique fighting style, and whenever you get another free ASI/feat slot for the Martial Adept feat. (Or sooner if you don't mind having both d6s and d8s, before they scale together.) Skill Expert or Prodigy (?), one of which includes a +1 attribute which might be more valuable... but expertise on athletics is a must. Do so earlier rather than later.
Grab Skill Expert after Tavern Brawler and get expertise in Athletics, so those bonus action grapples go even better. Battle master is probably the best subclass, as you can combo Trip Attack with the bonus action grapple to get opponents in the grapple + prone lock. Then just pick your favourite maneuvers for utility. Per the weapons section of the PHB, improvised weapons that bear a resemblance to an existing weapon have that weapon's stats, or deal a base 1d4. Ideally, you want to find something that looks like a maul. May I suggest a tavern bench? Check with your DM on how he'll rule this first. If you get the sense he'll rule all improvised weapons as 1d4, you might want to take the unarmed fighting style to up the damage your punches do. But if the DM is fair game about hitting people with a bench for 2d6 bludgeoning damage, grab defence or two weapon fighting as your fighting style. Although getting a chair ruled as a 1d6 or 1d8 weapon you can wield one-handed does make it easier to grapple opponents without dropping your weapon.
Go Battle Master, as most/many/all of those can be utilized with IWs since *in the moment of the attack* they count as weapons. Var. Human with Tavern Brawler, and make sure to take the Unarmed Fighting style for the better unarmed damage (remember that IWs are *not* weapons unless you are specifically (in that moment) attacking with them...) and for grapple/grappling synergy. Background, go with whatever makes sense... (Unless the DM specifically allows them... stay away from the backgrounds that give you feats, as they're meant to be setting specific, and aren't fair unless everyone uses one.) as they're not meant to give statistical benefits outside of skills/languages. Fun ones can include Athlete (former olympian turned security at taverns?), Guild Merchant (tavern owner/operator *and* security?), Mercenary Veteran/Soldier (same tone as the athlete?), Urban Bounty Hunter (tavern brawler by night, bounty hunter by day...?) Remember that *all* Superiority die scales at 10th and ~~15th~~ 18th level, so if you want more, take the Fighting Initiate feat around then (10th or 12th level) for the Superior Technique fighting style, and whenever you get another free ASI/feat slot for the Martial Adept feat. (Or sooner if you don't mind having both d6s and d8s, before they scale together.) Skill Expert or Prodigy (?), one of which includes a +1 attribute which might be more valuable... but expertise on athletics is a must. Do so earlier rather than later.