Companies to assess and minimise thermal loss in a house

[BallBallBallGame]

I have just bought a 1930s house and (even to my untrained eye) there seem to be lots of places where heat is escaping. Eg Thin (uninsulated) garage door, air vents, gaps between the skirting and floor etc. The EPC wasnt actually too bad but I feel there is definitely space to optimise.

There is loft insulation and double glazing but it is single brick wall therefore no opportunity for cavity wall insulation.

I plan to live here for a long time so I do not have a problem investing in this house.

What I would like to know is whether anyone knows of any companies who will come and do a detailed survey of heat loss / energy efficiency and then do the remedial works. Google tells me there are companies who will do an external thermal survey but it does not seem that they do the actual insulating work. And all the insulating companies seem to just be interested in loft and cavity wall insulation.

Many thanks in advance.

I am in SW London if that is relevant

Thanks!

I don't know if any companies, sorry, but my energy supplier Octopus hires out a piece of equipment that can detect heat loss. Worth checking if your energy supplier does the same?

I paid £400 for a survey by Ecofurb and have been a bit disappointed. They sent a surveyor to look at the house and assess its current construction, materials, insulation etc, then produced a report making suggestions about what needed doing, in what order. If I wanted to proceed with their suggestions they offer a further service of finding contractors and supervising the work. So far so good, but I'm not sure they really told me much more than I'd already worked out for myself living through a few winters in the house!