Hello Rob, I am in the UK and I have been using Rose’s recipes for the past 5-6 years with great success, in fact I prefer to use the recipes from Rose’s Heavenly Cakes in preference to all the many other baking books I own, American and BRITISH! I have also used recipes from the Cake Bible too, my version is the US one, which Rose herself recommended to me. I have not used bleached AP flour at any time but I have used American cake flour which I was given when a friend came back from a visit. SSHHH, it is not supposed to be brought over here!
The cakes I baked with the cake flour were perfect, a lovely soft crumb and they rose as expected. But I have also made very good cakes using our plain flour also. I used Kate’s method initially, using the microwave and it was successful but a bit long-winded and messy to be honest. I then tried supplementing some of the plain flour with cornflour and this was alright but a friend told me about using potato flour instead of cornflour and this seems the best solution so far. I am not saying the resulting cakes are comparable in a side by side tasting to those made with US cake flour but they are certainly acceptable and no-one has ever refused a slice (or two!) when offered. The ratio I use is one eighth of potato flour, seven eighths plain flour.
Out of interest, Shipton Mill Flour company sell a cake flour, it is not the same as the American flour as it is not bleached but I believe it is good and I know people who do use it are pleased with it. You can buy it online.
I hope you have as much success with Rose’s recipes as I have had, I’m sure you will be another convert someday soon. Let us know how you get on.