I don't think that one level of Wizard will let you scribe 6th level spells. When I've tried to scribe 3rd level spells with a 4th level Gale I get "Your Wizard level is too low"
If you want to embace the tankiness of the Tempest Cleric I'd suggest a Ranger 5/Cleric 7. This gets you up to 2nd level Ranger spells which have some great ritual spells like Longstrider, Enhanced Leap, Disguise, Talk with Animals. Plus you can get some good skills, can start with heavy armor via Ranger Knight so no re-spec needed ever, and can get some resistances.
Tempest Cleric 7 gets you 4th level spells.
Since Ranger is a half spell caster the 5 levels are like 3 levels of real caster, so your spell slots are based on 7+3 = 10th level 4/3/3/3/2 so you get 5th level slots that you can upcast. You could cast 3 Call Lightnings, 3 upcasted to level four Call Lightnings and then 2 upcast to level 5 Call Lightnings for 8 casts every long rest. You are the Thunder god.
For stats you can go with a 17 str or 17 wis with the other being 16, dex can be 10 since you are in heavy armor, put all you can in con and then do wahtever with the rest.
I like Dual Wielding for this since Rangers don't get two handed, plus there are some nice one handed non-finesse weapons. Dual wield the mace of Lathander and the Gnoll flail that heals you while activating the Ilithid psionic damage and go to town.
Melee in heavy armor is super survivable early and after you get your 2nd attack you add in the spell power.
I've got a Duergar doing this and he's a blast. Innate poison resistance plus fire resistance from Ranger help out a lot. High Wisdom helps out a bunch for saves and ability checks. Tiefling also starts with fire resistance and half orc would be great as well. Really any race would be good.
Its a very fun thematic character
