What database software are you using? and how are people accesing this database?

The best thing to do is to ask for clarification, if they want you to integrate it into Outlook or their e-mail server I think thats a bit beyond just Database design.

An Inventory table with the item_id,item_description

A loans table which will contain the item_id of items that have been loaned out, the date out, the return date, and any other info u need, you...

I think the error is because you are using different data types for the vehicleLicence on different tables, they are supposed to be the same.

Im not sure about the other stuff.

Well if you delete the link then there wont be anything for that message.

Why are you deleting the link? Also why not put the link in the message table as another Column?

Why not leave the UserId field alone and just update the name?
Then you can have another table, say History which will store all the edits a user has made.

I think you are reading the wrong stuff, star schemas and serrogate keys are used in Data Warehousing which is different from database design.
For your purposes I don't think that will be...

Cool.
I was thinking the score would be calculated from the Goals Table, but it might be simpler to include it your right.
The own goal thing seriously never crossed my mind:-O

I though about that(New diagram attached), but this means that my SQL queries are going to be much more complex, becasue I cant for example look for total goals scored by a player using just the...

When drawing DB relationship diagrams, do you usually show all the relationships? Because I seem to have lots of them and my diagram is geting very messy.
Sample Pic attached, I didnt even fill in...

option A for sure

I think it would bve something like this
DB Schema image attached!!