Boading, the speedboat, I got ready for my journey to the British Wastes! It was harsh, all i had was my Bobblehead, Nuka Cola and my Dog. Opon, arrival, i found a gigantic pigeon, fly above my head towards Downing Street.
Well boading should be boarding and opon should be upon
You don't need commas for "the speedboat"
You don't need to capitalize bobblehead or dog.
The bold sentence is a little confusing so get rid of all the commas, something like this. (Though am not the greatest at this stuff)
Upon arrival I found a gigantic pigeon, which was flying above my head towards Downing Street.And what the hell is this susposed to be anyway?