There is no definitive answer to this question as the cost of private healthcare in the UK can vary widely depending on a number of factors, including the type of care you're receiving, the provider you're using, and the location of the treatment.
That said, Forbes estimated the average cost of a private health insurance policy in the UK to be around £1,500 per year in 2018. This figure is likely to have increased in the intervening years, so you should expect to pay more if you're looking to take out cover now.
Of course, the cost of private healthcare is not just limited to insurance premiums – you will also need to factor in the cost of any treatments or procedures you may need. These can vary widely in price depending on the complexity of the treatment and the provider you use, but some recent estimates suggest that the average cost of a common procedure like a hip replacement can be around £13,000.
If you're considering taking out private healthcare cover, it's important to remember that the sum you pay each year is only one part of the equation – you will also need to consider the potential costs of any treatment you may need to receive. With this in mind, it's important to compare the cost of cover with the potential benefits before making a decision.