I'd get the pro's in - but ring around for the best price - they vary MASSIVELY in price. I had one last year and those wasps went absolutely MENTAL when he smoked 'em out and then blocked it up........
The council here use some kind of powder which they gently "post" through the entrance of the wasps nest. The wasps then carry the powder on their bodies further into the nest - and quietly die . We had no angry wasp and no fuss so I would recommend that method. Defo one for the professionals IMO.
I got rid of a very small nest myself (less than egg sized) from DDs playhouse ceiling by quickly putting a glass jar over it, then shoving strong card above it - sliced off quite easily as its only made of paper - and then just leaving the jar sealed up.
It wasn't swarming with wasps though, I think it may have been just a queen starting off then nest
We've had wasps nests two years running in the same place in our playhouse. Appears quite quickly, always spotted it when around the size of an egg and full of larvae. Dh does what Grimma does re getting it in a glass jar and then put water in it . Also, wasn't swarming with wasps.
DH has a tried and tested technique for wasps nests of regular (approx hourly) spraying of Raid and fleeing for his life, until the wasps are all dead. He then smashes up the nest. It sounds so cruel put like that, but we had a really bad infestation upstairs when DS1 was born, they were all over the carpet upstairs in the bedroom and landing, on my slippers <shudder>