Surrey Youth motorcycle club. They have the various size Ossets and a trusty TY80 for youngsters to try. They hold have a go events once a month all fairly close to J11 M25. Their most recent was this past Saturday. They have a facebook page and Dave Renham at InMotion' dad Eddie runs it. I am sure Dave can tell you when the next one is, 2nd Sat of the month rings a bell.
Depends on the rider (weight) and type of sections. Don't discount the 240 as well. The 200 (156cc) will feel very light and nimble compared to the full fat 250 of the 300. I had a 240 and then a 300, regretted selling the 240 as for some reason I felt it rode better and felt lighter but probably wasn't a lot in it. A young lad local to me does very well on a 200, but he is about 5 stone soaking wet.
Noticing where you are located and having lived in SoCal myself for 7 years I would lean towards which bike is more popular in your area and how close the nearest dealer is.
