Others might be able to recommend a better product. I just wanted to point out a couple of things.
Other than buying the foam cleaner-
https://www.screwfix.com/p/no-nonsense-foam-gun-cleaner-500ml/60133
Most cans of foam need shaking before hand and inverting to use them. I am only aware of one that works at any orientation.
be aware that when you finish squirting the foam, the stuff in the nozzle sometimes continuous to ooze out. I normally place the can on a plastic bag. Expanding foam can easily be removed from polythene but not so easily from floorboards/etc. If you do not plan to use the can for the next hour or so, hold the can upright and lightly "squirt" the nozzle. It will send the propellant out of the tube and clear it. If you do not plan to use the rest of the tube for a few days, remove the nozzle and spray the top of the can with the foam remover. If you plan not to use the rest of the can for a month or so, expect to bin it even if you used the foam cleaner.
If I have a tiny job and know that I am only going to use a very small amount, I purchase the expanding foam from the PoundShop. It is 2 quid for 250(?)ml
If you are purchasing the
Screwfix brands of filler perhaps consider buying spare nozzles
https://www.screwfix.com/p/no-nonsense-expanding-foam-spare-straw-5-pack/430hp
Additionally be aware that foam expands a LOT. Spraying surfaces with water will speed up drying time and adhesion. The propellants used are heavy and flammable. Do not smoke whilst working with them. If any foam creeps out of the gap at the top it can be sanded back with ease, but you may sand through the pre-primed finish.
The foam will not stick to your cat cables, which I assume will be in place before you fit the skirting but if you want to fit the skirting and pull the cables through, then foam is not the product for you. There is too much risk of blocking the void with excess foam.
