The taxable gain will be £208,900 (£320,000 - £100,000 - £11,100 annual CGT exemption) if the property is sold in the 2015/16 tax year. If the property has been your main home during your ownership of it, you will be entitled to a deduction from the gain for main residence relief and letting relief. Letting relief is not available if no main residence relief is due. See HS283
for more information.
There are two rates of CGT, 18% and 28%. The rate or combination of rates that you will pay will be determined by the level of your income in the tax year that you sell the property. Assuming you do so in 2015/16, one of the following scenarios will apply:
1 If your income in 2015/16 including the net taxable gain is £42,385 or less, then all the gain will be taxable at 18%.
2 If your income in 2015/16 excluding the net taxable gain is more than £42,385, then all the gain will be taxable at 28%.
3 If your income in 2015/16 excluding the net taxable gain is less £42,385 but more than £42,385 when you add the net taxable gain, then part of the gain will be taxed at 18% and part will be taxed at 28%.
If you give away the property, you will still have a taxable capital gain even though you won't have received any cash for it so, unless you have spare funds to pay the tax, that probably isn't an option. Such a gift would also be a potentially exempt transfer for Inheritance Tax purposes which would fall out of your estate so long as you lived for seven years after making it. Taper relief which you can read about here
may reduce any IHT liability after three years.
If the property is passed to your children through your will, then IHT at 40% will apply to that part of your estate which exceeds £325,000 or up to £650,000 if you are widowed and your late spouse's estate did not use the full extent of the nil-rate band available to it. Look here
for more information on the transfer of an unused nil-rate band.
I hope this helps but let me know if you have any further questions.