If its what I'm imagining, this is an upright tricycle, with three small (20"?) wheels in delta formation (one wheel at front, two at the back.) I'd be hesitant to take it on trails because:
a: I'm not sure the little wheels will treat you too kindly on the bumpy stuff
b: It might feel fairly tippy if the wheels end up in different ruts.
c: Whatever defences are added to cycle routes might well not admit something as wide as a trike.
d: You have three chances to line yourself up with a nasty (whereas a conventional bike having one wheel behind the other has only one).
Fortunately, the UK has a nationwide network of cycle routes called 'the road'. These are relatively well maintained and (assuming you have two brakes) are perfectly accessible by trike. There's no compulsion for a helmet and the decision to wear one or not is with you.
Bikehike, ridewithgps, googlemaps will all help you identify suitable routes, and a fair amount of fun (and miles) can be had by picking an arbitrary lane and following it. If you're not overly confident, check the gradients on ridewithgps before you set off. Anything called Church Hill is a no-no.
Does that help?
Andy.