I've completed my own version now!

I'll have a look at both your versions a bit later because I've got to work on somthing urgent now!

My own version very pretty complicated but totally configurable.

it expresses the "raw" time and days as an array of bytes.

So to set a lunch-break I just have to clear a BIT.

I then do a bitwise AND on raw time with each day an then count the set bits.

So far each day is an array of 6 bytes which gives the times to the closest half hour. I'll probably expand upon this to give the closest quarter of an hour because that will be close enough for what I need.