Hello your conservatory is probably underway by now and I hope you love it as I love mine!
Ours is not too big and it has a glass roof, in the sun it heats up really quickly but as soon as it the sun goes down it goes cold just as quickly.
We didn't have cenral heating in there as on a day like today we do not need the heating on in the house, however we do in the conservatory, and it would be a waste to heat the entire house just for the sake of the conservatory!
Ours gets the sun from midday until the evening and is so so hot in the summer, we have vertical blinds all around and pleated roof blinds they are both in white and in the sun it is still too bright, we have to wear our sunglasses in there, in hindsight we should have total block roof blinds, we are thinking of having a portable air conditioning system for this summer as it is a magnet for flies with the windows open.
On a cold but sunny spring day it really comes into its own, you feel like you are on the outside with the cold!
We have an oil filled radiator, and it is great, in the winter we leave the radiator on, on the 'frost' setting. we have a carpet and a fabric suite as opposed to conservatory furniture, and it gets very cold.
I call it the quiet room it is peaceful and great for reading with the extra light,also for watching tv when my husband is watching football! It is also nice to see the sky through the glass roof! And to watch the birds in the garden.
Even if its cold out but the sun shines it fills with heat and when we come in from work we open the door and let the heat fill the house!!