If anyone wants the best offensive spell a Warlock/Wizard can have without having a party member in that roll, any member can have Eldritch Blast.
At Level 4 you get your first Feat.
Choose "Magic Initiate : Warlock" and grab Eldritch Blast.
I gave it to my Rogue Thief, and still managed to get him up to Dexterity 20 by level 12.
Eldritch Blast also makes use of Sneak bonuses.
I do also have Wyll in the party with Hex and Eldritch Blast, but honestly I could replace him with any other character (Jaheira/Halsin/Minsc/Karlach) and not feel like the party is degraded. Quite often if swapping out a party member has been needed for parts of characters stories, Wyll gets left behind (I bring him back afterwards though because I do think he balances out the party nicely, but I don't consider him necessary).
Edit: Funny side note about my game - Gale, when I saw his hand beckoning me to pull him out of the portal, I just didn't grab it. "Nope nope nope, you can stay there you PITA"
so he's not an option to include at all.
