9 July 2017 Last updated at 14:27 BST
The How To Train Your Dragon author gave Martin some great writing and reading tips ready for the summer!

Thousands of people visited the blue flag beach over the weekend to enjoy the sunshine.
Independent Councillor Niamh Kennedy said there were only four bins on the 3km stretch of coastline and this created "mayhem".
The beach is a popular destination for visitors from Northern Ireland.
Local people collected the rubbish from the beach on Sunday and Monday after visitors had left.
The refuse left behind included deck chairs, barbecues, food waste, glass bottles and nappies.
Paul Diver, from the Sandhouse Hotel in Rossnowlagh, said the majority of people that visit the area "behave impeccably".
"A bigger issue is traffic and the lack of toilet facilities, there were three portaloos and our hotel became the public toilets for the weekend," he added.
Cllr Kennedy agreed that a lack of toilets and traffic management at the site were causing problems.
"Once the sun comes out it's bedlam," she said.
"Cars are allowed on the beach-but there is a safety issue."
"The cars were blocking the entrance, then the tide comes in and there's a big scramble, every year there are cars destroyed."
She added: "If there was something serious you would never get an ambulance down."
Last year cars got caught out by the tide at Rossnowlagh beach.
Cllr Kennedy said council resources were insufficient to properly look after the beach.
"The resources are not there," she said. "It will be a community effort to try and address the issues, but council will have to help and back them up."
She warned: "The beach could lose its blue flag status if this keeps up."
The council said the amount of litter left on the beach was "extremely disappointing".
"Donegal County Councils Litter Management team had a presence on Rossnowlagh beach over the weekend and they carried out clean ups on Tuesday and Wednesday," it said in a statement.
The council said that its traffic management plan had been reviewed and they are working with the local community."

Kayla Mueller was abducted when working in Aleppo, Syria and died last year.
The woman charged - 25-year-old Nisreen Assad Ibrahim Bahar, known as Umm Sayyaf -  is currently in Iraqi custody.
Prosecutors say Sayyaf kept Ms Mueller captive, allowing her to be repeatedly raped by IS chief Abu Bakr al-Baghdadi.
Nisreen Bahar's husband, Abu Sayyaf, is described in an affidavit as IS minister for oil and gas, reporting directly to Baghdadi.
Abu Sayyaf died last May when his compound in Syria was raided by US special forces.
His widow was handed over to the Iraqi authorities for prosecution.
A US justice department statement said they supported the prosecution but would "continue to pursue justice for Kayla".
"We will always be relentless in our efforts to identify, locate and arrest those who are responsible for the kidnappings and murders of American citizens," said the FBI's Assistant Director in Charge, Paul Abbate.
Mueller had travelled to Syria as an aid worker when she was kidnapped in 2013.

Cloth Of Stars, Humphrey Bogart and Red Verdon are the other supplementary entries at a cost of £75,000 each.
Irish trainer Aidan O'Brien has seven of the 18 contenders still in the race, including leading hope US Army Ranger.
The additional entries mean the race will be worth £1.454m and the most valuable ever staged in Britain.
If all 18 horses line up, it will be the largest Derby field for 10 years since the victory of Sir Percy in 2006.
O'Brien, who has won the race five times previously, saddled eight runners in 2007 when his best finisher Eagle Mountain was second to winner Authorized.
Martin's behind the scenes at CBBC's Summer Social and caught up with author Cressida Cowell.
[NEXT_CONCEPT]
A Donegal councillor has complained after visitors to Rossnowlagh beach last weekend left "huge amounts" of rubbish behind.
[NEXT_CONCEPT]
The widow of a former senior leader in the Islamic State (IS) group has been charged with conspiracy in the death of a US hostage, US authorities said.
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Four horses including joint favourite Wings of Desire have been added as late entries for the Derby at Epsom on Saturday.