Do you think I will able to survive jumping off of a top floor of a typical height of British home?

You don't jump, you dangle and drop. Preferably on to a lower roof (porch/ground floor extension) if you can, otherwise push the bedding & mattress out of the window first to cushion the fall. You may break an ankle but you'll survive.

It depends on the building height. What are you considering an average?

I told my kids to jump onto the roof of the car parked under the window.

you might but if you did survive or did not survive you would certainly cost the taxpayer a lot of money

May not keep a rope upstairs.

i did

If you have wings, Yes..........