Yes there are rules. The overriding rule is that the sentencer should have regard to the totality principle.
Normally all counts will receive a sentence. Broadly speaking, offences arising out of the same incident will be sentenced concurrently. However, that is not set in stone and for example, possession of a gun whilst committing another offence (eg criminal damage or drug dealing) will often result in a consecutive sentence. Offence whilst on bail, resisting arrest, or violence to escape from another offence will attract consecutive sentences.
The sentencer should announce whether the penalties are conc or cons - if not it is presumed they are concurrent.