You can get these Freezer-cooling blocks for literally 1 euro each, they will help to keep the temperature down.
You keep these for about 6 hours in the freezer, after which they are frozen solid and will stay cold for a long time. You can pack them together with the food and keep it for quite some hours of travel. This way I have successfully transferred cheeses on a 5 hour bustrip + 3 hour flight, and 2 hour train ride. (all in a row).
Only downside is that, due to the extra liquid, you will need to check your bags.