Any advice on what I can fix or change? I am trying to get this house uploaded to the TS2 lots & housing category.

AS it is now, I don't think it would be accepted. First of all is the floor plan. Do you see how you have large rooms that seem multi purpose? Like for example gym equipment in the lounge room. You need to find a way to arrange it so each room is more dedicated. So there should be a wall so the living room is just the living room and the gym equipment should be in a gym room. The cribs should be in a nursery, the chess and other items could be in a living room but don't go into a kitchen. So I would work on the floor plan first.

Is the roof an auto roof? That isn't allowed either, try using a gable roof. You will also want to remove some of the windows. With a large back yard you will find it looks better if you put down some pavers especially around the pool from the back door and add a BBQ area close to the house.

Holey cheese, those rooms are huge! And it looks very boxy from the street. You could slice one whole row of squares out of the bathrooms and still have room for a cat box or potty chair in them. I like large, open living plans, myself; but consider room dividers or changes in floor treatment to indicate differences in use areas. You could have tile in the food prep and exercise areas, for example, and wood in the public areas, reserving carpet for the private space of bedrooms.

For the landscaping - that's a lot of flowers to water! Vary the landscaping some more and use floor tiles (stone or poured) and terrain paint to indicate high-traffic areas. I don't see a door leading directly from the house to the playground area, which is a natural thing to have.

The effect from the front is very boxy. Consider a porch or patio to vary the visual line; or possibly extending or recessing the side rooms from the rest of the house. If you extended the master bedroom and the exercise area out by one square, you could easily retain the formal symmetry while dividing the interior space into two separate rooms on either side, as Jo suggested, without making any of them feel at all cramped in comparison to the rest of the house (especially if you've bought some more space by shrinking the bathrooms one square as I suggested).

If you don't have M&G, roofs are a pain in the neck and there's a limit to how good you can make them. You can, however, do better than the autoroof. Changing the footprint a little would help by providing more roofline variation from the front view.

I recommend that you get the entire rest of the house the way you like it, go away for awhile, and return when you are fresh and mentally prepared to conquer the roofing tool. Then play around and experiment with it. Do mixed gable and hipped roofs. Figure out how shed roofs work. Get the hang of the way the orientation of the roof keeps shifting around on you as you drag it (I promise, there's a logic to it). Stick in some dormers even though you don't plan to have a usable attic, just to break up the roof line, and see how you like them. Ask yourself "what does this button do?" and find out (remembering that you have an "undo" button). You're not on a deadline and can take all the time you need.

Imho, i wouldn't put an external door in a bedroom (unless it's a balcony or apartment), especially one for children, and yes I do agree it looks kinda boxy from the front, so I'd knock off a few tiles if I were you. Also, I'd tone down the windows.

Looking at the back view, I'd remove those two windows and doors and put in those pricey modern glass doors, seeing as they are leading to the same place and you have enough tiles to make it look good.

As for the floor plan, I agree with Jo, I think you'll need to shift it about a little to accomodate the kitchen and the gym equipment. As much as I love the ensuite, you could knock a wall down and place something there. But that's entirely up to you, as this is your house.

For the furniture, I'd make it a bit more matching imho. Use your SPs and EPs to your extent! Here's a tip from me; once you've placed your furniture and happy about it, play with the walls and floor tiles, you never know what can match! Look further down the catalog! Also, there's no harm in placing some masonry inside, mix and match the walls, mix and match the floors!