TGA /FDA/EMA/MHRA, page-3

MHRA in the UK does not have the same function as TGA/FDA.
MHRA does not certify medical devices, it monitors them.
CE/UKCA certification carries significant weight, equivelent to TGA/FDA, because it allows for the sale of medical devices.

From the MHRA website-

Medical devices
The MHRA is responsible for operating the UK medical device vigilance system. This includes carrying out market surveillance, enforcing the legislation and working in collaboration with healthcare and regulatory stakeholders both in the UK and worldwide.

Before a medical device can be placed on the UK market it must have a UKCA or CE certificate. This certificate shows that the device meets the relevant regulations. For higher risk devices (Class II, IIb or III), this certificate must be issued by an independent “UK Approved body”. Low risk devices (Class I) do not need to go through a UK Approved body and the manufacturer can self-certify the product before placing it on the market.

While we don’t certify medical devices, we do have oversight of UK Approved bodies and have powers to remove medical devices from the UK market if we feel they are unsafe.

In exceptional circumstances, we can issue Exceptional Use Authorisations (EUAs) allowing medical devices to be used that have not followed the standard approval process.

Individuals and manufacturers can register their devices with us, but this does not equate to an “approval” or certification.

https://www.gov.uk/government/publications/more-information-about-the-mhra/more-information-about-the-mhra--2#medical-devices