An organisation called London Aid for Ukraine is coordinating collection and dispatch of specified supplies to Ukraine.
Details of what to send and how to send it are available on their website.
It has a dispatch point in Enfield:Enfield Delivery Guys
South Lodge Farm
251 Enfield Road
EN2 7HX
(Green and yellow sign: South Lodge Farm)
Opening hours are 08:00 to 19:00 Monday to Saturday.
Contacts at the dispatch point are:
Anatoly 07908 908590
Roman 07473 779996
However, you are asked not to phone unless absolutely necessary because they will be busy.
They use their own vehicles to transport materials to Lviv, from where it is distributed.
They only want medical and military supplies that are on the priority list - nothing from the Other Humanitarian category.
