My place built in 2000 has no roofing felt. I don’t know why as you can buy it. In my case the loft insulation sits on the ceiling with paper vapour barrier. Yes it is hot up there in summer and cold in winter. But house fine. I topped up to 40cm or whatever the norm was a few years back. No condensation as plenty of gaps in the tiles and some air tiles.
Proposed solutions sound good. Personally if I had the roof off I’d put some felt under it doesn’t seem right to have the loft as outside your house space. The loft door has 10cm foam attached to it and any wall touching a room is insulated but only to height necessary.