If you are looking to bye a new bike you should definetly look on here. http://www.tartybikes.co.uk/ They have a great range of bikes on there all depending on your buget. Or if you dont want a new bike and just somthing to learn on have a look on ebay. Personly i found that a mod (20") is easier to lern on becuse they are small and esay to chuck around, but seeing ass your quite tall you might be better suited to a stock (26"). You should try and find some trials bikers in your local area and have a try on both kinds of trials bikes and see which one you prefer. And no you are never to old to start trials biking.