The answer is yes you can however bare in mind that this will create a permanent hole on your bead and frames should you wish to replace or remove your window covering in the future. Remember that your windows is built to last for a long period of time more than the blinds that you are installing therefore you have to think twice (or thrice) when drilling a hole into it
Things to consider before drilling and screwing on to uPVC
Do you have the right screw? a particular screw is required to ensure that it will hold for a long period of time, specially with moving parts of the blinds and windows when operating, an ordinary screw in a plastic when it is moved regularly will eventually loosen and fail
Do you have the right skills? precision and angled drilling for example to ensure you don't hit vital components of the windows (such as glass, supporting joints and mechanisms) damaged.
Understand the internal mechanism of your window/door
Check with your manufacturer/supplier if this action will void the warranty of your windows
Check with your manufacturer/supplier if the product that you are installing directly to your window is a product that they recommend
Check with your blinds/window covering provider if the product that they are supplying will suit what you require and will not void the warranty if not, have this in writing
Is DIY drilling and screwing is your best option or should you get a professional to do it for you and ensure that they know what they are doing and understand what you require.
Bottom line is to make sure that you don't damage your beautiful uPVC window and its functionality. Use product to complement, functional and proven thru time to maintain the beauty and integrity of your uPVC window. We believe that we offer the best solution in no drill window covering and it has been used over a long period of time in Europe. For us a no drill option will still be the best option and far less risk in damaging your uPVC window.