Premium Economy is currently Mushrooms, Mushrooms or Mushrooms...not very good if like me you can't stand mushrooms...Economy should be different so you should be ok !
Sorry, not a route I do so can't be much help, I'd suggest looking for Trip Reports covering evening flights into Gatwick for the past month and you may get some guidance.
rldl1977 is correct in so far as mushrooms have been making an appearance in a lot (ok.. all) of the PE meals recently, think it may have changed though and we are safe from that mushroom scourge (for now... ): )