Let me start with an analogy relating to food hygiene:
If you try to find SPECIFIC legislation which states that people involved in food preparation must wash their hands after visiting the toilet, you won't do so. All that the law (as laid down by Parliament) does is to lay down GENERAL principles, requiring those involved in the preparation of food (and those supervising them) to maintain certain general standards. It's up to restaurant bosses to lay down specific rules, and to ensure that they're observed. Local public health officials can also make it clear as to which rules they expect catering establishments to adhere to.
Similarly, there's very little written into statute law as to SPECIFIC requirements in relation to fire safety. It's up to the landlords (or freeholders) of properties like yours to ensure that the GENERAL principles of fire safety are adhered to. They can therefore make their OWN rules, which tenants (or leaseholders) are expected to observe, in order to comply with their legal obligation. Also, where a property requires a fire certificate issued by the local fire service, the Chief Fire Officer can insist upon certain rules being put into place before a certificate is granted.
All of which (regrettably) means that we're not really in a position to advise you. There is no GENERAL rule relating to the proximity of parked vehicles to multi-occupancy properties, but your landlord (or freeholder) might have imposed such a rule as a condition of tenancy (possibly at the insistence of the Chief Fire Officer for your area) in relation to the particular building which you live in.
You should ask the person who insists upon parking 10 feet away from the building whether they're doing so because they believe that it's a statutory requirement or whether it's because it's in their tenancy agreement (or lease, as appropriate). If it's the former, you can tell them that they're wrong. If it's the latter, they may well be correct.
Chris