Will I regret not extending my home?

[BorneoBound]

I live in a reasonable sized 3 bed semi. Downstairs consists of a lounge, kitchen and dining room - it is big enough for our family of 4. The kitchen is rectangular, roughly 2.5m x 7.5m so while it isn't big enough to be an 'entertaining' kitchen there is plenty of space for all the kitchen cupboards we need.
I have come in to some money which is enough to extend the side of the house to make the kitchen double the size. Is it worth it? We don't spend lots of time in the kitchen, but large kitchens with islands etc always look so nice. Having said that though, a big chunk off of my mortgage instead is also very appealing. What would you do?

How old are your DC?

Doesn’t sound like you’re that fussed about the extension so I wouldn’t bother tbh

How much would it add to the value of the house vs how much will the work cost?

If I didn't need/want the extra space a lot, the gain in value would need to be significant before I chose to extend over paying down the mortgage.
If the extra space would hugely improve our quality of life and enjoyment of our home, I would be happy if the cost of the build broke even with the increase in value.
Living in a building site is hellish even when you really want it done, so I'd want to be 'compensated' for the upheaval, be that financial or quality of life.

I'd pay a chunk off my mortgage, your kitchen sounds a decent size with enough storage, why spend thousands of pounds making a room bigger when you don't need the space.

Would it add the same amount of value to house as the works cost.

It depends if you’d think you’d like to eat in the kitchen and then use the dining room for something else such as a playroom, teen room, WFH room, woman cave etc.

I would pay off the chunk of mortgage then put aside what you save each month from that and take some time to think if you want to use that to extend in a few years.

To answer some questions, DC are 12 and 14. The house would likely increase in value roughly by the cost of the extension, however we don't plan on moving so overall house value isn't a huge motive either way. We wouldn't consider making the extended kitchen a kitchen/diner as the dining room is off of the kitchen and has views of the garden which is my homes wow factor - I have no real use for a teen room / kids room / woman cave.

I wouldn't bother then and would pay off some of the mortgage and also have a few nice holidays.

Reading your update I wouldn’t bother either.

All I can say is that if you don't need don't do it

Especially as works can go horribly wrong for a variety of reasons or costs can go up etc

Thank you everyone, you've been really helpful