Thanks stayola,

I do plan to continue to work on it, and the app should eventually display the results without a redirect to the tfl site (hopefully it'll be a lot quicker than waiting for the browser -- well, I find it a bit painful anyway)
mysociety have a perl based tfl scraper that I may be able to learn from and modify to my needs. If anyone knows of any other way to get this information, I'd be grateful.

As for customisation options, I've found some into on the URL format here: http://wiki.opentfl.co.uk/TRIP_REQUEST2 -- so that "should" be straightforward too (and useful to have)

On the TODO list is to also fire off requests to Traveline when you're outside london. This is made extra annoying by the fact that the travelline websites all handle only certain sections of the country and don't handle journeying from one section to another.
So, for the time being, if the start or end is outside london, tflapp fires off a redirect to google transit (well, outside london, but in England as google transit does not cover all of the UK) -- annoyingly, google transit in the UK does not do trains. So the results are currently pretty rubbish there too!

Just remember that this is all very new to me (I'm not really an "app developer" either) and could hence take some time to get working...