Help! Can't Figure Out How To Break Down Tables.

First of all, thanks for any help in advance, I really appreciate it. This is my first big project in Access. I am trying to design a database for timesheets for all the departments at work. We have 21 departments with various numbers of employees in each department. At this point, I would like this database to be able to have users enter their own hours each week and print their individual report of hours worked then designated users add employees, look at previous payperiods and print out a master report as well as past reports. One pay period here is two weeks, with the days starting on Saturday, though I would like the database to keep track of one week at a time and then be able to group two weeks together to make a pay period. Each employee can work regular hours in a day and can also take up to 6 type of leave plus work overtime. So there will be 8 types of hours that could be entered. So far, I made tables for each different type of hour and created fields for each day of the week and created relationships to the employee table and pay period table. I made a form in datasheet design, but it didn't work out well. For lack of a better thought for them to enter their hours, I was going to design the form to look like this (but with spaces like a table);

Employee(fn) Employee(ln) Payperiod

Sat Sun Mon Tues Wed Thurs Frid Totals
Regular Hours
Vacation Used
Comp Used
Sick Time
Overtime
Holiday
Unpaid Leave
Paid Leave


The only thing is that I can't get the forms right and it seems like a lot of wasted space since employees will rarely take holiday, paid leave and unpaid leave. Is there a better way to design this?

I also have to take into account security. I eventually have to be concerned about departments only having access to their own records and employees within those departments only being able to access their own hours (except for designated users to do the master sheet). I haven't had any training or experience in access database security. Is there a way to limit records in a table or would I need to create a seperate database for every department?

I am attaching my table relationships in case I didn't describe this very well.

Thanks again for any help. If you need any further information, let me know.