New blood!

[acuna]

Ive just decided after a few months of debating and procrastinating (and many of years riding my pushbike up unknown trails and roads) that im gonna get off my arse and go on a year long adventure. At 19 money will be tight so am still unsure whether im going by bike or just trekking it.
So can people supply some rough costs? I'm thinking in the region of £5000 to get going, that includes all bike, kit etc... What is fuel gonna come to, ill be in no real rush so intend to do some work as I go along. Also what are the time lengths allowed in country's in general? are they all over a month for instance?
Another major concern is insurance though, what are the problems with this concerning younger riders, can I get it and will I need it (read about someone who spent less not having it even after having his bike nicked and getting ill) as I will most likely be travelling alone? (unless I meet a willing lady by next year .

I have no off-roading experience and as i'm planning on Asia or S.America was wondering if this is wise? I guess i'll learn as i go along but at the moment it consists of London and Kent riding on a (now being restored and in boxes) 125 Superdream.

Any help greatly appreciated and as im intending to do this next year theres no great rush, just gathering info (and cash).

Another odd question is what do you people do for work when you return? Is it hard to find work, and does/will it turn into just funding the next expedition?

P.S. Thanks for supplying the very useful site and good luck to anyone whos riding around now or about to go!