"Can anyone give me a rough budget"

US $3000 for flights (airtreks.com or trailfinders.co.uk are usually a
much better deal than Star Alliance or One World RTW tickets), and
another US $1000 for local transport. US $1000 for visas,
vaccinations, and insurance. If you are backpacking, your expenses
should range from US $15 per day to US $50 per day depending on where
you are. Those are absolute bottom figures, and you might prefer to
pay a few extra dollars to avoid roach-infested rooms and 14-hour bus
rides. There are some expensive things that you probably would want to
take advantage of, like the Inca Trail in Peru, adventure sports in New
Zealand, or a safari in South Africa. Overall I would estimate US
$10000 per year in addition to the US $5000 mentioned above for a total
of US $25000.

"and also point me in the right direction as to where there are savings
to be made?"

Spend a large fraction of your time in the least expensive countries
and regions - India, Southeast Asia, Peru/Bolivia, Eastern Europe, and
the Middle East. Also, spend more time exploring countries beyond just
the capital city and one or two major tourist destinations - they will
often be much cheaper off the beaten track.

"I'm estimating about a 2 year round trip, working as and when I
need/want to."

It can be very difficult for a Westerner to find work in developing
countries. It can be almost impossible to get a work visa or to find
anything even close to a Western salary. If you are running low on
cash, your best bet is to spend time working in Australia or New
Zealand, or to teach English in Japan/South Korea/Taiwan.

"I'm thinking i'll fly to munich, then train to moscow, then fly to
delhi, fly to bejing, fly to hong kong, fly to bangkok, fly to
melbourne, fly to auckland, fly to suva, fly to lima, train to brazil
fly to SA, fly to egypt and then fly back to the UK."

You'll need to take plane or bus or boat to go from Peru to Brazil.