I think you need to clarify your thoughts about what you would like to gain rather than list what you have already decided to do.

It sounds like the current kitchen dining room is not big enough for you (although it does seem big enough to have an island without extending), you want it to be lighter and you want obviously garden access.
It sounds like you want an over sized laundry room.
It sounds like you want two additional rooms that connect to the hallway.
It sounds like you want more storage.

Instead of stating what your plan is why not state where the opportunities are? For instance it sounds like there is room to extend at the back and you don’t need to keep a garage so that could be converted.

But you may have additional opportunities you have not considered, for instance there may be room upstairs for the laundry you want, or room to extend in front of the kitchen or to the side. It may be that you don’t know how you are going to use all the bedrooms and so if you want additional rooms to work from home they may help. It may be that there are limitations as the garage may be at a different level to the house or have a low ceiling. It may be that the plumbing is all on the right of the house and it’s not possible to have any bathrooms or laundry on the left. And because of the cost of moving there may be budget limitations that limit what is possible.

So please add a little more detail specifically how many rooms you need, pictures, the upstairs plan

Utility room should be at an entrance that you are happy to use as everyday entrance - or at least every time you come back to the house with muddy dog/boots/whatever - if you have space to the right of house then the current bathroom makes sense to become utility.

Interesting change CDW. I'll definitely explore this suggestion. Thank you so much

Thanks Jonathan. To clarify, I haven't made any decisions yet, which is exactly why I'm here looking for feedback and suggestions. Thank you for coming back to me anyway and offering your help.

The kitchen and dining room feel like a reasonable size to us. The main reason I considered opening up to the conservatory was purely about light. The space faces north-northwest, so connecting to the conservatory seemed like a way to bring in more sun. Again, we're open to suggestions.

Above the kitchen, there's a water cylinder and small storage space.

I'll share photos of both the conservatory and the kitchen.

Additional info in case it's helpful:

. The garden is large, sloped and wide, with a timber outbuilding at the end that has electricity but needs some repairs. There's also a side entrance to the garden on the right of the house.

. There is a driveway that fits three cars, so we don't feel we need to keep the garage.

. The current garage and kitchen were added as an extension to the original house.

What we would like:

• A lighter kitchen and dining room connected to the garden, with an island (no hob or sink on the island)
• A separate living room or partially connected to the kitchen and dining area
• 3 bedrooms, including a guest room
• 2 studies
• A playroom / snug
• 2 bathrooms — downstairs we'd like to remove the bath and keep the shower
• A utility room with a large sink, a drying rail, and space for coats and muddy shoes with easy access from the entrance or garden
• A coat and shoe cupboard in the hallway

I'm also attaching the upstairs floor plan.

Any thoughts or suggestions would be really appreciated. Thank you.

There is an issue with the app as Houzz is not letting me add photos. I'll try again later

Yes this app is temperamental.
If you are unable to attach new images to the original post then you should be able to add them in the comments.
If you are using a phone you sometimes don’t have the option to select photos….. in which case close the app and reopen it.

Moving the water cylinder above the kitchen would allow you to add skylights and this may well be a more cost effective way of getting more light without replacing the conservatory.

You should consider if you really need to replace the conservatory or if you can get additional light by making the dining room doors bigger or by upgrading the roof on the conservatory gain the extra sitting space you want.

Additionally a light coloured floor and worktop will change how light the kitchen feels. Perhaps the three windows it has are enough

I was just thinking that removing the chimney might improve the downstairs layout, if you were to extend I wonder if you would have a bigger bang for your buck by extending the outside study. And I wonder if the master bedroom could be bigger and grander by moving it downstairs.

Wow Jonathan, that floorplan gave me food for thought! Removing the chimney depends how much it costs. I was looking at a way to have an open and nice view to the garden from the main entrance and it seems this is a way of achieving this.

Hopefully we can move the water cylinder above the kitchen somewhere else so we can have skylights instead of extending the kitchen and dining room.

Thank you so much. I'll be looking at and exploring your suggestion in the next few days.