Conservatory or extension?

[Dizzywizz]

So we had someone out to quote for an extension off the lounge yesterday, it will be to create a dining space - we have a decent sized 3 dbl bed bungalow but the lounge is small, dining table in the kitchen makes the kitchen feel small. Extending up not an option, I am disabled.

Anyhow, the upshot was £30k extension but the builder thought a conservatory much better option for us - 10-15k. I am worried about conservatories being too cold in winter too hot in summer? Will be south facing, with radiator, French windows and roof windows, laminate floor pos a rug.

And are conservatories passé? I've never really liked them but the cost saving and how he was saying he has one which is perfect all year round and I have seen some modern designs on Pinterest....any thoughts?

Thinking it will be an extension, and we will get one more quote. Thank you for all your advise, it's been really helpful.

We have a conservatory for the past 10yrs (put in by previous owners). I cant' remember the last time anyone sat in it. We store stuff there but we have to be careful what we put in it since the light fades strong colours. I would love to remove it but it's high off the ground, connected to decking and has a double sliding door from the the kitchen so it's a faff to take it away. It's a very bright shed!