A family from Norwich is among several from across the country who will deliver a petition to Downing Street today calling for more access to medical cannabis.
The 'End our Pain' campaign will see 16 families, including the Hughes family from Thorpe St Andrews lobby the government to raise issues including the lack of prescriptions for medical cannabis given out by NHS doctors and delays in getting hold of the drug.
The visit coincides with a hearing by the Commons Health and Social Care Select Committee, at which the UK's chief medical officer Professor Dame Sally Davies will give evidence on the availability of medical cannabis after it was announced in November that specialist doctors can prescribe the drug.
The change of law means full extract medical cannabis made by a good manufacturing practice-certified company can be prescribed on the NHS.
Ali and Matt Hughes, whose 19 month-old son Charlie suffers from between 40 and 50 seizures a day, will be among those delivering the petition.
The couple have asked for prescription of full extract cannabis in the hope of controlling their son's seizures after primary and secondary epileptic drugs failed to have an effect but were told Charlie did not fit the criteria.
Speaking to the BBC about the campaign Mr Hughes said: 'I think the government are years behind in their knowledge of cannabis, there are numerous European countries that are far ahead with clinical trials and with evidence, I think they need to act now, there's children, as we speak in hospital having life threatening seizures and it only takes one to kill them.
'We need to act' he said.
The couple have also been in touch with Hannah Deacon, the mother of Alfie Dingley, a youngster from Kelinworth, Warwickshire who has severe epilepsy.
He was the first person in the UK to receive a permanent medical cannabis licence and went on to be granted the first NHS prescription issued after the UK law change.
He was having up to 400 seizures a month but since the prescription, he has had just one hospital admission in a year.
Tonia Antoniazzi, the Labour Gower MP who co-chairs the All-Party Parliamentary Group on Medical Cannabis Under Prescription, said: 'Patients and families were given so much hope when the law changed in November.
'Now all we see is despair. All of the families gathered at Westminster today have tried many powerful pharmaceutical drugs over the years, all with severe side effects, to help stop their children's seizures. They haven't worked.
'The Home Secretary changed the law quickly, now we need to ensure that a policy is put in place by the Department of Health and Social Care that actually lets patients get access. For these patients in particular, it's a last hope of relief.'
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