Flea bath for kitten- what’s the UK equivalent for blue Dawn dish soap?

Hello everyone,
We just got a 7 week old kitten that had been rescued from a pretty terrible hoarder situation. He finally let me stroke him today and he is absolutely covered in flea dirt so we need to bathe him as he’s too little for any topical or oral flea treatment. I keep reading about blue Dawn baths but we are in the UK- does anyone know what is equivalent to blue Dawn here? I’m terrified of using something that’s not safe for him! Any advice appreciated
Thanks in advance