Yes I tend to make up as I go on also, according to what I find in the shop.
For me, a fish pie needs white fish, smoked fish, salmon and prawns... and a Dukan bechamel sauce... and maybe some cauli mash on the top if PV? Some sliced cooked egg between the two layers?
Let us know!
I have the recipe book... I'd prefer it were illustrated personally but there are some good recipes and I like to have things in a book, rather than all my loose pieces of paper and post-its everywhere (which I'll still have of course!)