It will be just as difficult for a true Somerset person to understand you as it may be for you to understand them. Get somebody to tape you speaking - you probably won't even be able to understand yourself! Here are a few terms that are used in ordinary conversation - believe me, it won't be long before you are incorporating them into your everyday speech!
Yerr Yes, a greeting or pre-cursor to a sentence
Yertiz Here it is
Wasson? Whats on?, Whats going on?
Backalong In the past, a while ago
Gone on Moved along, passed away
Get on! Stated in a surprised way - almost disbelief
Wheres he to? Where's he(or she) going? Where you living to?- location?
Youm You are
Innum/Inner Isn't it, aren't you
Isser Is it? as in 'She stuck isser?'
Gurt Great, as in size - Gurt big gammon (on a pub menu)
ee It, as in give 'ee over 'ere
I Me, as in 'Give 'ee to I'
My luvver Term of endearment - as in 'Youm alright my luvver?'
There are plenty more examples, too many for me to include on this site. The important thing is to find out for yourself. It's the only way you can truly appreciate the people and County of Somerset.