I'm not sure why Access split your data up in that manner. You understand your data and what you want to use it for best, so I recommend separating the data into discrete tables on your own. If you're interested in learning about the general philosophy for separating data into tables I recommend researching "data normalization".
From what I can tell, what you should try to do is this:
1) Create a table named tblVenues. This table will hold only information that pertains to the specific venue (not different gigs the band has played there)
- Venue ID, Venue name, City, Country, Capacity
2) Create a table named tblGigs. This table will hold only information that pertains to a specific gig that the band played in the past.
- Gig ID, Venue ID_FK, Date, Tickets Sold, Fee, (Idk what you meant by %, Net, or Gross in your description).
Some general notes about this: Each table needs to have what is called a Primary Key. This is a column in the table that will serve as an ID number to distinguish each entry into the table (VenueID, GigID are examples I've provided). The next step would be to link the tables together (Notice I included VenueID_FK in tblGigs... that FK stands for foreign key. This is essentially a link to the table tblVenues by way of VenueID. What this allows you to do is be able to compile multiple Gigs at a single Venue without having to repeatedly enter all of the data for that specific venue into your datasheet each time you create a new Gig. You're using a single number 'VenueID' to tell the computer which venue the gig was at, and it can just look up the rest of the information about that venue if you happen to need it.
Unfortunately this is only the start of your journey mate. What you're ultimately trying to do doesn't sound like it would be all that difficult if you had a firm foundation in how relational databases operate, but it seems you have some learning to do on that front. Hopefully this will get your feet wet. I recommend watching some of these
videos. The guy is describing how to build a booking system for a hotel, which doesn't sound extremely helpful, but he walks through data types and some of the basics of normalization in the first few videos. Stumbling upon them was an absolute godsend for me (I'm pretty new to Access as well) so I think they'll do you some good. Good luck!