Imo, warlocks don't make great frontliners. They're better put up high, and using the hex(spell)/eldricht blast(cantrip)/agonizing blast(invocation) combo to nuke people from afar. What you're looking for as a frontliner would be a paladin which isn't available yet, maybe an eldricht knight fighter, or a melee ranger. As for Gale, idk how you managed his stats but make sure to max out his intelligence and (same goes for all ranged characters) make sure to give him high ground, the difference is huge. You could use misty step to put him in a better position.
As an aside, nothing beats clerics for support roles. They're not necessarily exclusive healers, since you can prepare new spells every day, and offensively oriented clerics can be really scary.
