I've got a leaking shower cubicle. After running the shower for about 30
seconds, a steady stream of water starts dripping from somewhere near
the back wall.

The shower fitting itself is on a side wall, so I don't think this is a
problem with the pipes. I've resealed around the shower basin with
silicon sealant, but the drip keeps coming.

I reckon it's getting in through the grout somewhere. Plausible?

I'm a complete novice when it comes to things like this - is the best
plan to re-grout the tiles on that wall? If so, is that an easy job, and
can anyone recommend a good source of instructions?

Thanks

Drew