If the house was valued at probate for £100,000 and you sell for £122,000, there is a £22,000 capital gain. If the house is still in the names of the executors, this is a gain in the hands of the executors. Once the executors' CGT allowance is taken off, the rest of the £22k is taxable.
HOWEVER, if the house sale proceeds are not needed to pay any of the costs or liabilities of the estate, you can "appropriate" the house to yourself and your brother and have the executors sell it as bare trustee (appropriation is only a paper exercise). That way the gain is £11k to you and £11k to your brother. You can then use your unused personal capital allowances to potentially wipe out the gain and so no tax is payable.
However, if the probate value was £122k, there isn't any gain and isn't any tax.