Under Building Regulations Approved Document B Volume 1: Dwellinghouses, there should be a vehicle access for a pump appliance to within 45m of all points within a dwelling house. Any street or private drive forming part of such a fire access way must be no less than 3.7m wide between kerbs (though this may reduce to 3.1m for a gateway or similar short narrowing) and should have a minimum centreline bend radius of 6.55m (or 7.75m if enclosed by walls) and headroom of 3.7m. 

There should be vehicle access for a pumping appliance to blocks of flats to within 45m of all points within each dwelling (Approved Document B Volume 2: Buildings other than dwellinghouses) 

The access way including manholes should be capable of carrying a 12.5-tonne vehicle, though structures such as bridges should have a minimum carrying capacity of 17 tonnes. A cul-de-sac that is more than 20m in length must have a turning head of at least size 3. Where there are flats of more than four storeys there are additional access requirements; for more information, refer to the Building Regulations and/or the local Building Control Authority. Fire access will normally be to the front of dwellings, but rear access is acceptable provided it is clearly signed and the dwellings are also numbered from that side.