A 6 Lore Bard/1 Barbarian tank gets:
-Rage (for half damage from most weapon attacks, 2 Rages/day)
-Unarmored Defense (boosts AC with DEX and CON mods, can still use a shield)
-Shield (spell, Additional Magical Secrets, for fights when you're not raging)
-Mirror Image (spell, Additional Magical Secrets, for fights when you're not raging)
-Cutting Words (d8s, Font of Inspiration replenishes all uses at Short rests)
-Defensive Duelist (best feat option, add proficiency bonus [+3 at this level] to AC when using Rapier+shield)
-Lucky (feat, only Variant human can get a 2nd feat by this level, increased chance for enemy to miss)
-Martial Adept (feat, another option for Variant humans, gain defensive maneuvers like Parry and Evasive Footwork)
Yeah...prioritize DEX and CON before CHR and nobody can touch you. I recommend against taking Valor Bard with this build because you lose Cutting Words (Valor bards get Combat Inspiration instead which makes others tanky, not you) and you also lose your defensive spells like Shield and Mirror Image (though you can choose Magic Initiate feat to gain the Shield spell back, but not worth the feat when there are better options).
If you really want, you can drop Barbarian altogether, but you won't be tanky as a straight Lore Bard until Additional Magical Secrets kicks in at level 6 (don't bother with DEX and CON if you're straight bard, just go all CHR for more Cutting Words). 1 level of Barbarian lets you tank pre-6 though (let's face it, most campaigns are lower level) and Rage+Unarmored Defense are still useful all the way until level 20.
Font of Inspiration is so
ing overpowered. Need Cutting Words every round of every fight? No problem.