Shift Rota for work

Good morning guys, happy xmas and all

I was wandering if somebody could help me. Basically im creating a rota for my place of work. The conditions are
1) 5 days, 2 off
2) 4 days, 4 off, 4 nights, 4 off
3) 4 days, 4 off, 4 days, 2 off

Im having trouble with 3) as im using the true/false arguements
Also when a day shift I use the letter 'D' but when its a night shift, i am unable to use the letter 'N', again as im only using TRUE/FALSE arguments.
Also the rota will need to be edited from time to time with holidays (H), is there anyway it can be edited without the formulas being deleted from the cells.
If anyone can assist me if be of great help

Hi, for a start I noticed that cell B4 is wrong....I'd make it =B5

So it looks like you have a 37 day rotation, on the 38th day employees go back to the start.
What I did was make a simple 37day lookup table across the top with the assigned day or night shift.
Then I added a column after the employees name where you enter a start number that signifies what day of the 37 day roster starts on this roster.
Each day then uses that start date to lookup the shift from the table. There is also an End number at the end of the roster.
That End number is the last day of that roster, so for the start of the next roster add 1 to that number for the start.
So in the example here, it says 25...so next months roster you will enter 26 as the start number.

I hope this idea will work for you.