Door Handle Loose - Name of Replacement?

What exactly is loose?

That looks like the first of the upvc handles and when you say the handle is getting loose that's just how they go as they were purely just pressed and flanged into the flat base of the handle. The newer ones are designed better and more secure. I've used that company @10-10-20 posted the link of and found their handles to be very good quality. Fitting is very straightforward just changing the screws. New ones provided with new handle

They are extremely easy to replace.

Take a look at this link.

https://www.homesecureshop.co.uk/blogs/news/how-to-identify-and-measure-your-upvc-door-handles?srsltid=AfmBOopBYcV0O12MJ5L56OnJOzmaB36ZcWktCN23pyaFUKrOKkFeG5ed

You want to measure the dimensions and order a matching one. A and B are your most important dimensions. For Dimension C you could get one a bit larger, but if it is smaller then you'll see the outline of the old handle once installed.

Just get a good accurate measurement and you're good to go, order on line and then swap it out. Easy peasy

I dont see any measurements on woodies, take a look at screwfix if they are near you - better filtering and prices.

https://www.screwfix.ie/c/security-ironmongery/door-handles/cat6760002

something like this is what you are looking for i assume - https://www.screwfix.ie/p/mila-prolinea-lever-door-handles-type-b-pair-polished-chrome/9379g