To work out if there is a capital gain in the UKyou need to convert all figures to pounds sterling. You can convert your 50% from USD to GBP for the purchase price and purchase costs, using the official exchange rate in at the time of purchase.
Do the same for the disposal, to work out your gain. You will need to apply the UK private residence relief rules, help sheet HS283 will help.
HS283 Private Residence Relief (2022)
There is also a capital gains calculator that can help.
Tax when you sell property