I recently learned that in the US you can defer capital gains on a property sale, and use the capital to buy another without paying taxes using a 1031 exchange.
Is there something similar to that in the United Kingdom?
Assuming that what you want is a way to roll forward a capital gain on an investment property you’re selling, to the purchase of another investment property, then the answer is no. The capital gains tax becomes payable at the time of sale and the tax liability can’t be rolled forward or deferred. If the property you’re selling was your primary residence then there’s no capital gains tax liability at all.