Cavity Walls - thin film internal insulation?

Hi all, looking for advice and experiences people have had.

We have some uninsulated cavity walls. Now I know that they can be filled, but the quotes I have had have been rather expensive! ~£3K, and I am looking for something I could do myself if possible.

I have seen people talking about internal thin film insulation, but the info I have seen is for solid walls. So the question: Could I apply it to the interior of my exterior cavity walls? I know I could put it on the internal walls.

This would mean I could do 1 room at a time and spread the cost a little. Also should I fill the cavity in the future, then hopefully they will work nicely together?

Thanks in advance

I’ve never heard of thin film internal insulation, you may need to be a bit more explicit. Do you have any links?

3k for a cavity fill sounds like a lot to me but I’ve only seen the generic costs (like this How Much Does Cavity Wall Insulation Cost In 2020? | I’ve not actually had someone come out and quote.

The thinnest stuff I’m aware of is the areogel impregnated blankets (slentex I think) it also comes as a backed MgO board. It’s high performance but gets very expensive if you want to do more than a small area.

I suspect they increased the price due to the green homes grant… I will look at getting another quote soon. Thin film insulation is really something I have only heard of on here, in another thread.