Can anyone identify the manufacturer/name of the window casing here? Post questions and find answers on glazing, double glazing, upvc glazing, conservatory glazing, fixtures and fittings etc....

[kieronbutler]

I want to replace a double glazed window with a uPVC panel (and dog flap). The casing surrounding the window has screws at the bottom and on the left side side only. The horizontal casing has no screws at all. Before starting the work, I would like to know the correct way to access the window - but so far have been unsuccessful in finding the appropriate instructions online. If I knew the correct name for the casing, or the manufacturer details, I am sure I can find appropriate instructions. Or if you can offer advice on how to make the replacement, I'd be very grateful. Thank you.