All state schools require pupils to study all three sciences up to at least GCSE level, usually as either a double (equivalent to 2 GCSEs) or triple (equivalent to 3 GCSEs) award.  Students can find they require support in each of the three sciences at different times.  Alternatively, students requiring support in one science, may find that they occasionally wish to cover material from one of the other two subjects.  I am happy to offer this service, meaning you do not need to find an additional ad-hoc tutor to fill these gaps.