"will I get a tax return for the difference for first half of the year"
You never get a tax return. Your tax return is the form you send to the government that shows your income and calculates your tax. The money that the government sends back to you is your refund. The government does not send your return to you. You send your return to the government. After you do that, the government sends your refund to you, if you are due a refund.
Your refund is calculated for the whole year. The amount depends on your total tax for the year and the total amount that was withheld from your pay. It doesn't matter when during the year the tax was withheld. The refund is not calculated separately for parts of the year, even if you changed your withholding mid-year.
The filing status on your W-4 is used only to determine how much gets withheld from your pay. It doesn't matter if it doesn't match the filing status on your tax return, or if you changed the filing status on your W-4 during the year.
