None of the places we stayed at supplied an iron or kettle. So a cheap travel iron and a little kettle might be a good idea if you need a tea or coffee kick start your day.
You should also note, in case you did not know, that whereas the English seem to have colonised Tenerife, the Germans are in the large majority on La Gomera. I would swear that I heard far more German spoken than Spanish whilst we were there recently (Jan 2010).
These boots are made for walking...Surely some clothes suitable for walking or trekking .Nothing too warm,a coat will do.
And here is a photo of playa de las Inglais at Valley Grant Ray