A Lowestoft man who sexually assaulted a schoolgirl after walking into a house uninvited and sneaking into her bedroom has been jailed.

Kyle Lambton, 37, had been drinking whiskey and taking cocaine during the day prior to the incident on March 13 this year, Ipswich Crown Court heard.

Lambton went into the house around 1.15am and entered the girl's room while her father and brother were downstairs watching television, Marc Brown, prosecuting, told the court.

He put his hand over her mouth and began kissing her forehead before the girl was able to scream and alert the house, Mr Brown said.

Family members confronted Lambton and he then left the house, the court heard.

Lambton was arrested and in police interview explained he had been drinking from 2pm on March 12 at the Lord Nelson pub in Lowestoft.

He also admitted he had consumed around a gram of cocaine, which was something he did every week.

Lambton also told officers he had no recollection of what happened.

Lambton, of Avondale Road, Lowestoft, previously pleaded guilty to sexual assault but denied a charge of trespass with intent to commit a sexual offence.

Those pleas were accepted by prosecutors, and Lambton appeared for sentence on Friday.

Matthew Sorel-Cameron mitigating, said Lambton was "utterly ashamed" of his actions, but had no recollection of the incident.

Mr Sorel-Cameron said the offence was 'out of character" for his client and that Lambton understood the impact his actions have had on the girl.

He added that Lambton was frank with police about his condition on the night in question and told police: "I'm wasted".

The court heard that Lambton did have previous convictions but had not offended since 2012 and had no previous sexual matters.

Judge David Pugh said Lambton had taken "an excessive cocktail of alcohol and drugs" during the previous day.

"Although that might be an explanation," the judge said. "It does not excuse your behaviour."

Judge Pugh jailed Lambton for three years and imposed an indefinite sexual harm prevention order.

He was also made subject to notification requirements until further order.