Greetings and welcome to the forum st3rius
Like what Sam say's, hondas good and easy to pick up parts etc. You need to do your CBT before anything else to see if biking is for you
If your 24 you should be able to choose between the A2 test (and ride up to a 33 bhp for two years after the test) or the DAS test which is ridden on a larger bike, if you pass this test your not restricted to the size of bike you ride after.
I saw somewhere on the net that restricting a bike costs anywhere between £50 to £150. If you do a google search you may find more info.
There are some thread which have links to insurence search engines which you could use to get some idea of the cost of insurence :-
Bike insurance cheapest I found tesco insurance