Toby my cockapoo has decided that he no longer likes wet food on it's own, so I have been feeding him Naturediet dry food and like you I wanted something on top, so he has about 50grams of the Kibble and 25-30grams of Forthglade 'Just Lamb' meals 3 X per day. and this seems to suit him fine.
Forthglade 'Just' meals come in a variety of flavours including Duck, Turkey etc and are, as you would expect, 90% meat and 10% water, maybe these would suit Rhodri? They don't come in gravy as such but maybe worth a try.