Re: Is the QR code check part of the app in a legal requirement for venues?
Couple of useful quotes from "Official Sources":
https://covid19.nhs.uk/pdf/how-to-guide.pdf
The app currently supports Apple iOS versions 11 and higher, and Android versions 8 and higher. If you have an older smartphone whose hardware is incompatible or uses an older version of the iOS or Android operating system, you may be asked to update your operating system.
Ho-ho - update my smartphone's Android v5.1 to v8? How?!
https://faq.covid19.nhs.uk/article/KA-01137/en-us?parentid=CAT-01035&rootid=
If I do not want to check in to a venue with the NHS COVID-19 app, am I still allowed to enter?
If you do not want to check in to a venue using the NHS COVID-19 app, you should be able to provide your contact details as an alternative. You have the right to choose to provide your contact details if you prefer this to using the NHS COVID-19 app.
Customers or visitors to hospitality venues must do at least one of the following:
* scan the official NHS QR code poster
* provide their name and contact details
* be in a group for which one other member has provided name and contact details
Hospitality venues must refuse entry to those who do none of the above. If you choose to check in with the NHS QR code you do not need to provide your contact details as well.