If you are due to make an income tax payment on 31st July 2020 then you have the option to defer this payment until the 31st January 2021.
If you complete a tax return and you are struggling to make the payment due to the impact of COVID-19, you can defer the payment.
The income tax will be payable by 31st January 2021 and there will be no interest or penalties for deferring the payment, provided it is paid by the 31st January 2021.
Bear in mind, on 31st January 2021, in addition to any deffered income tax, the balancing payment in relation to 2019/20 and the first payment on account for 2020/21 should be paid. This could mean you would be paying a whole years tax liability at the same time.
If paying taxes in general is a struggle, it is possible to agree with HMRC on an instalment plan, to spread out costs, but there will be an interest charge on late payments.