I am a british user of CC and was wondering if anyone had a good basic sponge and frosting mix which I can add monin syrups (coffee/cocktail flavouring syrups) to flavour them

I have looked at some of the basic recipes but these include American cake mixes which are not easy to find and are very expensive when/if I do find them!

Has anyone tried this with any success? Can anyone share any recipes to get me started on this.

Just FYI I cant get cake flour in the UK either (unless someone knows of a substituition)

All answers appreciated