Is a small extension pointless?

[Yodaismyspiritanimal]

Hi all,
I'm really struggling to visualise a small extension and if it's worth it, I can't seem to find any pictures on line of what I'm thinking of.
We're about to buy a 1950s infill semi detached house with separate garage. The floor plan attached is very similar except the lounge has already been knocked through to the dining room. So our plan is to knock through from kitchen to dining room (and maybe have doors put in between dining and lounge). It looks unlikely that we'll be able to afford extending the kitchen/dining room out by the 3m we were hoping for, but it's possible we could afford 1m...is this just pointless, will it make a decent amount of difference?
The current measurements are:
Kitchen 3.73m (12'3") x 2.51m (8'3")
*
Lounge* 3.73m (12'3") x 4.44m (14'7")
*
Dining Room* 3.99m (13'1") x 3.25m (10'8")

You should definitely wait until you can afford 3m as so much of the costs will be the same (steels, foundations, equipment hire) whether you do 1m or 3m. I really wouldn't bother with 1m.

I don’t think it would be worth knocking out the back wall just for an extra 1m. Better to wait until you can afford more, or possibly build a small extension to be a utility room, without knocking down any walls. That could be cheaper if you did a small lean to conservatory type extension off the kitchen door.

Thanks both, I do appreciate your responses. I totally get it, but I guess I'm just conscious that it would take us another 10 years to save up what we need, and by that time we'd be looking to downsize again! Sighhhh there's always the lottery!!

@Yodaismyspiritanimal

Just wait a few years for house to rise in value then borrow against the equity to fund. That's what most do!

With all the sunk costs I can't understand how a 3m extension is significantly more than a 1m one. A 1m one won't really add any value either (unless you are in somewhere like Mayfair!). Best to wait...