Hello. Will I get a tax penalty if I wanted to withdraw my 401K early to attend school?

Yes, you will owe a 10% penalty for early withdrawal, plus income tax on the withdrawal (federal and state, if you live in a state with income tax).

Yes, withdrawal from 401(k) for qualified education expenses is subject from early withdrawal penalty. On your tax return, the additional tax is reported on
Form 5329, Additional Taxes on Other Qualified Plans (including IRA's), and Other Tax-Favored Accounts, to report the penalty.