Gear ratios for no brakes riding...

I've done richmond park brakeless (as well as other), it wasn't a problem at all.

This is a good place to start if you like to have some cycle training;

http://www.lcc.org.uk/

'peace bro'.

A much better place to start with cycle training is actually http://www.cycletraining.org.uk/. Or your local authority, which may offer free or subsidised courses for adults. The LCC site covers far more than just cycle training.