Build a 'lean to' extension after removal of conservatory - should we?

[AlwaysaLittleBitTired]

I have a notion to remove our existing hardwood conservatory (has a glass roof) and build an extension that would be accessed from the back of the house through exisiting doorways from the kitchen and lounge. It would be 'lean to' with no need to knock through any walls and there would be no fittings such as kitchen cabinets or anything similar. A set of bifold doors and probably a tiled sloped roof (possibly with velux or two). I have no idea how much this is likely to cost, but I am hoping I can do it inside £20k. Am I way out?! I have seen the price per square metre theories, but how realistic are they really? It would be L shaped, and approx 30m sq total.

...and is it true and I can sell my old conservatory? It's a nice one. Maybe I should just stick with what I have.

We need new windows for the house and I thought of increasing the mortgage to fund those along with the new extension (DH not at all convinced about the extension, but the fact is we never use the current conservatory as it is cold) as we have capacity to do that.

Anybody done anything similar who can give the benefit of their advice/experience please?

I don't think you can get that big an extension on the budget. Also, what would you use it for? Do you actually need it?

Allow £1000+ per metre of bifold (at least that was my measure in the SE). You can price off the shelf roof lights online www.glazingvision.co.uk/rooflights/fixed-rooflights/

I was surprised how expensive building with glass is compared to blocks. So then you'll know what change you'll have left from £20k

THanks both

JoJo - no, we don't really 'need' it, but it would be a vast improvement on the cold conservatory and if open from the kitchen we would be drawn in to the new loveliness . We already have 2 small sofas that would live in there, I would also have a desk in one corner for working from home (and for the family computer as currently struggling with where to put one) and at the smaller end we would have a breakfast bar type thingy with a couple of stools. You see, I have it all planned!

I have spotted the new 2017 extension thread, but don't feel I'm yet qualified to join..at least until we're committed.

DidIReally - thanks, that is really helpful to get some idea on cost. I think I need to talk to a friendly builder...