Hi Reedswood,
Thanks for replying. As you say, if it's the seal cracked then it's probably best to get the garage to sort it. However, I was hoping to check that it actually is the seal before I go to them, so I need to get the gutter trim off first, to take a look, and I don't know how to do that.
I'm not completely sure it is the seal, because the water seems to be coming from around the triangular access panel behind the rear light cluster, then in over the plastic trim below the panel. I don't want the garage to charge me for investigating, then say that it's something not covered by the warranty.
Many thanks
Sarah