Hello, if you have an idea then a gap year can be the best time to start your business!
I went on a gap year two years ago, but really didn't find any of the gap year websites useful when I was planning what to do for 12 months. Before I took the gap year I worked at a summer camp in the USA for 2 years but found there were no independent guides / info about working at camp. Also I ended up paying a fortune for volunteering with elephants in Thailand when in reality you could turn up and do it for free, which really annoyed me that the UK based gap year websites didn't offer this information!!!
So on my gap year I planned a new range of travel websites, from working at summer camps, taking a gap year to general travelling. Take a note book and keep jotting down ideas whilst you are away. You will find you have so much time (inbetween having the time of your) to plan a business, sometimes travelling can get boring so it is good to keep your mind focused on something productive (other than sitting on a beach for 3 months etc)
Also there is internet everywhere around the world so you can research and do work, in Australia a lot of the internet cafes are free so you have plenty of time to write up a business plan.
When I got back I put all my ideas I put together whilst away into practise and now run a popular range of websites helping people to work, volunteer, take gap years & travel worldwide (which all started when I was on my gap year).
I would welcome the chance to help you further if you need any advice or anything, if you have the idea don't let anything hold you back!