Recs for handymen for woodworking project

Hi,

This might be a bit of a weird one to put in a forum of amateur enthusiasts but I have a home woodworking project that I am fairly sure is outside of my (limited) ability. Does anyone have any recs of good professional handymen/carpenters in south london?

Basically I have a 60s flat with single glazed crittall windows which look nice but as windows have the efficacy of tissue paper. Secondary glazing isn’t possible, and neither is replacement, so I’m looking to build a kind of frame with a locking mechanism that would house some perspex that could slide away to allow for the window to open. It’s kind of tricky and pernickety for a few reasons hence not attempting it myself.

Any advice welcome! If anyone has crittall windows please share your experience lol.