How do you get into Modelling? In the UK.?

Hi I'm really interested in doing some modelling. Im a teenager who is 5ft 8 and am repeatedly told how I do look like a model. I would be interested in doing fashion and editorial modelling. Do you think the best way is to apply to some agencies like Models1 and Elite? BTW, i do not have an eating disorder. And I am of a very healthy weight before anyone says lol. Are any of you models? Do you have any advice? I have a friend who used to be a glamour model but thats not really very helpful..considering I want to go into fashion.