There are a variety of things that you can do to either avoid paying capital (legally) or at least postpone it. First of all, you should utilize your annual allowance (used to be around 10,000). In addition, both in the US and in the UK, there are capital gains reliefs which can be provided.
For example, in the UK, if you dispose a business asset and you invest the proceeds, then you are eligible for roll over relief and no capital gains tax is paid. You will pay capital gains tax when you dispose the second asset but if you again invest the proceeds, you can once again claim this relief. In the US, the primary residence up to $250,000 is exempt from capital gains tax.
There are quite a lot of reliefs and you can search them on the HMRC or the IRS website. Another thing you remember is that you can use capital losses incurred in previous years to offset capital gains.