It's been a while since I had my Skoda rapid (same shape) but I think that there should be a flap inside the boot at the same side that you can use to access the actuator from inside. Either that or you might need to pull the carpet back. I know that there's something that comes out as I changed my tail lights to the Monte Carlo tinted ones
I think that it's a generic VAG part - the one in my Scirocco R wouldn't unlock and my mate's A6 wouldn't stay shut