First of all, I like the character!
Thomas is a very light-hearted boy and very believable. He's not a brave superhero kind of guy. I also like his sense of humour and the overall plot.
The funniest part was his enthusiasm while telling the story and his fondness for apples.
Even the plot is pretty good. It had me chuckling for a good time. It was a good mixture of suspense and humour.
That was pretty cool. That bit about the curse being laid on the family for years to come sort of comes true in GoF, right? I like Thomas. He seems very childish, but in a good sort of way.
You managed to transmit Thomas's child-like innocence so well your writing. His child-like confusion and fear at the dragon's arrival.
I think you'd need to elaborate on this line though: "an escaped dragon lands on your house, a curse is brought upon your family for generations to come" -- what sort of curse? - a little bit of detail would had been great ^_^
Did you like my description? I hope so! I plan on being a poet one day. (maybe 'writer' will be a better term than 'poet', since he uses prose over rhymes. ^_^)
It took him several hours to recover, while Mum Apparated to the King to inform him of the dragon. (Spells are usually italicised and I think you need a comma here as well)
Will’s Dad had to keep casting spells on it to stop the Muggles from noticing and several neighbours got really scared. (a missing word)
Great characterization on Thomas and a light and amusing plotline.