How doesn’t the constitution protect the rights of citizens?

Any acts can be repealed because no entrenchment.
Parliament is sovereign and therefore can go against the judiciary when they want.
In the case A and others v Secretary of State for the Home Department (2004), the Law Lords declared that the indefinite detention of suspected terrorists at Belmarsh prison was incompatible with Article 14 of the ECHR because the Act discriminated against non-British citizens.
In response, the government introduced the Prevention of Terrorism Act (2005), which replaced the discriminatory detention of foreign nationals with ‘control orders’, applicable to British and foreign terror suspects.
Following the ruling in HM Treasury v Ahmed and Others (2010), the government introduced the Terrorist Asset Freezing Act (2010), to give them the anti-terrorism powers the judges found they lacked.

Brexit will not prevent cases being taken to the ECHR, but repeal of the HRA might render ECHR decisions less effective and the UK will not be bound by changes to EU law.
Following the 2016 EU referendum, the Government proposed a Great Repeal Bill, which would repeal the European Communities Act, and transpose all existing EU legislation into UK law.
UK courts would be unable to prevent Parliament from amending or repealing any of the rights and liberties that are carried over.
While politically challenging, it is equally possible for Parliament to repeal the HRA, which would obviously further limit the courts.

This transparent access to information is crucial to protecting rights however the FOI Act’s effectiveness can be challenged by the fact that 37% of requests were declined in 2016.