May depend on your local by laws etc? check with your local council. What have your neighbours got its usually an indication? Modern estates are often limited to between none to 3ft? But areas do vary so a quick check with your local council will soon tell you it may be on your house plans/deeds.

So far as I know - no more than 4 foot in front of house. But why not take the time to check your council's rules - we only know vague generalities.