After trawlling around several conservatory companies we settled on POSH Windows & Conservatories. Their showroom had an example of the sort of structure we were looking for. It needed a large amount of brick rather than the traditional conservatory which is almost 100% glass. This is because we wanted to use the room all year round and at all hours of the day. Technically this becomes an orangery.

Additionally, we liked the salesman and their practice of employing builders instead of contracting them out.