Grooming
Starting points: 2 years custody if the victim is 13 or over but under 16
Sentencing ranges: 1 - 4 years custody
http://www.cps.gov.uk/legal/s_to_u/sentencing_manual/s15_grooming/
Sexual activity with a child
It depends on the activity. There seems to be a general belief, and the latest article link seems to concur that this was kissing. This would come under "Contact between part of offender's body (other than the genitalia) with part of the victim's body (other than the genitalia)"
Starting points: Community order
Sentencing ranges: An appropriate non-custodial sentence
http://www.cps.gov.uk/legal/s_to_u/sentencing_manual/s9_sexual_activity_with_a_child/ (includes recommendations for other types of contact)
The links also contain aggravation and mitigation that can affect the sentencing.
Thta's the UK for you. What if it was in Germany?