Congratulations on your purchase -- I hope your first season goes well!
I would suggest that you got to Halfords or somewhere similar and invest a few pounds in a set of tools to keep on the boat permanently. Otherwise (if you're anything like me) you'll forget to dig out what you want to take from your main tool kit and only realise when you get the boat on the water
This should cover most eventualities:
- small tool box
- screwdriver with variety of changeable bits
- small socket set
- small spanner set
- pliers (regular and long nose)
- side cutters
- plug spanner
It's also worth packing a tin of WD40, some cable ties and a roll of gaffer tape. If this lot won't fix it, then it's broken
Don't buy anything expensive as it will get trashed by salt water, or dropped overboard. Don't got to the other extreme though and buy tools from the pound shop, as they will break when you most need them!