Bruno Girin

Hi all, My name is Bruno. I just joined on the recommendation of a friend as I am in the middle of a renovation project on the French windows at the back of the house that open onto the garden and would appreciate advice. The house was built in 1934 and the windows may be as old as the house. It is a wooden frame with 2 opening panes in the centre and 2 fixed panes on the sides. I noticed the paint was flaking off so decided it would be a good job for a bank holiday weekend to strip the paint and give it a new coat. I then realised that it has at least 5 layers of paint of different ages and the sealant around the glass units is flaking suggesting I should renew it. As I'm in for a more complex project than initially planned, I wondered if I could take this opportunity to replace the single panes of glass with double glazed sealed units. I am aware that double glazed sealed units would be a fair bit thicker than the current single units. So my questions are: Can it be done? Where can I get double glazed units? How can I size the thickness of the glass + spacer? Do I need to fit the new units differently than the old ones? Will the weight on the frame increase and is that a problem? I attached some photos of the windows. Thanks! Bruno