Can you make self raising flour out of plain flour? what do you need to add?

[Isababel]

I'm doing a cake tonight for a party tomorrow morning and have just realised that the one and only recipee that DS can have due to allergies specifies "self raising flour". Well, I have just "plain flour" or even "bread flour" and plenty of little bits that I can add to it (yeast and the like).

Can I add something to the mix to make up for using plain flour? or do I have to make the tiresome journey to the supermarket?

Thanks in advance

this might help

A few teaspoons of baking powder with the flour .

What LizS says, and use the plain rather than the bread flour.

Thank you for that, I was dreading the trip. I will see how it works (I'm working with glutten free plain flour and it is only stocked -sometimes- by a single supermarket. )