Bubble wrap versus window film to reduce heat loss -what works?

[TheOwlAndThePussycatCannotSwim]

Tempted to tape bubble wrap onto the very old single glazed windows, but have seen numerous shrinking window film products that promise to reduce heat loss and save money on heating.
Do they actually work? Any recommendations gratefully received, I have just bought radiator foil and teddy fleece sheets to be prepared for the autumn, but I want to do the windows now.🤔

We use this. Easy to put on, easy to take off. And it works.

https://www.diy.com/departments/diall-clear-window-film-l-4m-w-1-5m/1802835_BQ.prd

Also cheap curtains and sew cheap lining in makes a massive difference. We did this until we got our new double glazing. Shut curtains early in the winter. You can just throw up old fleecy blankets over your curtains when shut but a bit of a faff.

This is better.

The window film works, but you have to apply it carefully. Clean off the paintwork with rubbing alcohol or similar. When the tape is in place, run over it repeatedly with a soft cloth before removing the paper layer. When you are blow drying it, again go over pressing the tape down with a soft cloth, ensuring as sealed as possible. Be careful not to touch the film with the hot barrel of the hairdryer and ruin your careful work!