Likelihood of theft

I'm planning on getting my first bike this year (125cc) just want to know if its even worth the risk if I don't have a garage etc. I live in a flat and there is steps just to get up to the ground floor and even if it was fully level with the ground I would be causing a fire hazard and blocking the door. It is a bit recessed from the road however and I could probably get away with keeping a smaller bike (125) on the path leading up to it.

Obviously, I would use a cover as well as disc and chain/D locks but I just want to know straight up if its even worth the risk if I can't keep it indoors. If it helps I live in the south east of England in case anyone else from around the Reading/Bracknell area is in a similar situation in regards to bike parking.