You can bring the £124K to the UK, but Capital Gains Tax will be payable.
To declare the Capital Gains Tax on your tax return, you need to work out the calculation of the gain, using pounds sterling only.
You will need to convert the purchase costs and expenses into pounds sterling, using the exchange rate in use at the time of purchase.
You will also need to convert the disposal value, costs and overseas tax paid, to pounds sterling, using the exchange rate at the time of disposal.
You can then work out the gain.
The official exchange rates can be found here:
Exchange rates from HMRC in CSV and XML format
If you need to look back further, the arhived rates can be found here: