Kitchen extension

[Where2start75]

I wondered if anyone could suggest what they would do if knocking this wall/door through to an extension? Photo hopefully attached!
I'm planning on extending so the deck area you can see is a living / dining area.
The kitchen is small and currently L shaped- I'm standing with my back to the rear surface.
I'm keen to extend the surface round to the right, in line with where it currently ends, and have shallow cupboards on the kitchen side and breakfast bar on the outside.
What I can't get my head around, is how much of that wall with shelves I should lose when knocking through. The shelves are handy!
I need to get it right (I think), so that a rear door in the extension doesn't block any potential work surface.
Thanks for your thoughts or alternative ideas.

Do you have a floor plan?

@Tortephant here's a sketch

Structural considerations aside,I'd lose all of it (the wall). There is literally nothing on those shelves that couldn't be rehoused v easily!

@AllJoyAndNoFun thanks! I have very little surface space and cupboard space at the moment but I think you are right. It probably seems a trivial decision but has become a bit of a sticking point in proceeding.

You are trying to make what you have fit a new space.
start with a blank bit of paper and draw and re draw and do again lots of options for how you will use all the space. How you will move around it, sit in it, work in it. Forget about budget for now, design it to your ideal.

my concern is the cost of this to the value of your homes I’m not sure it’s financially sensible.

@Tortephant
I've been quoted around £40k for the extension (3.5m x 3.7m). To a degree, the added value is irrelevant - I've been here 20 years and am unlike to move in the next 10 if ever.
It's a good sized house, 4 bedrooms but with a small kitchen that opens onto a big garden. That means we spend lots of our daytime in here as it feels like the centre of the house, so the additional space would be very well used as a living / day area.
The kitchen itself is 18 years old and not in desperate need of replacement so I'd do that further down the line, but obviously need to ensure it'll all work together. I think that's why I'm trying to see how to 'add on'.
I'll try the blank piece of paper - good suggestion

If you have bifold like the diagram , you do not need a back door on the other wall. Use that other wall as a wall full of floor to ceiling cupboards, with minimal handles. Or put floor to ceiling cupboards either side of your current door to the kitchen.

Forget about a breakfast bar - you gain nothing and the space is too small for it to be useful.

extend your counter space and put a bench seat under the window in the dining area - you will save seating space and can use the bench for storage- my sister uses hers for pasta; sauces; tinned food. It’s really useful.