Have a look at how to videos on youtube. It's not overly difficult to do yourself.
Agree with above - really a 5 minute job.
Took it to the shop, never been to the one i went to before, guy was really good. He sorted then rear derailleur out quite quickly, he said some angle thingy was out and the derailleur was a little loose. He also kindly took my front derailleur off cleaned it up, re-lubbed it and the gears change very nicely now
Cost all of £10
Also noticed he does rear suspension servicing for £50 sommet so will get him to do that when i need it.