Oh dear!! I would call a specialist/exterminator as that sounds quite dangerous. I don't know of any in particular, not very helpful I know but a quick google should help you locate someone in your area.
Might I add if I had wasps in my conservatory I would be completely terrified (insane fear of bees and wasps!) and may consider moving house lol!!!
Do you know where the nest is? Can you get to it easily? I had the council sort mine out, but when I saw what they did I thought, "I could have done that myself". You can buy DIY spray. She sprayed the nest during the day when most of the wasps are out. A few popped out to see what was going on but it was very un-dramatic! Disclaimer - I am not recommending you do it yourself of course!
Aree they actually wasps? There are smaller insects that mimic wasp appearance but actually aren't?
Are they coming in because they are attracted to plants in your conservatory? Is there an actual nest you can see?
Ant powder sprayed liberally on the entrance to a nest will kill it. Do it at night or very early morning before they start flying. I always do it this way after a council exterminator told me that is all they use to kill wasps nests and easy to do yourself.
I saw a £3 aerosol spray to kill wasps' nests, after I'd paid a man from the council £45 to deal with the nest. However, he used all-over protective gear and had dozens of them flying around him after he'd sprayed, so I think if it happens again I'll be phoning the council again, just too scared of multiple stings.