HSC Safety Forum (Northern Ireland):
Kings thrombosis centre (England):
Patient information leaflets: NHS Choices website: Deep Vein Thrombosis.
NHS Choices website: Pulmonary Embolism website: Prevention of Deep Vein Thrombosis website: Deep Vein Thrombosis website: Pulmonary Embolism
NICE guidelines on the management and prevention of VTE can be found via these links:
Reducing the risk of VTE
Management of VTE

Nice have also recently produced Quality statements for VTE management which can be found here:
SIGN have a single document for the Management and prevention of VTE which can be found here:
British Orthopaedic Association:
Royal College of Obstetricians and Gynaecologists have produced the following 4 guidelines:

Thrombosis and Embolism during Pregnancy and the Puerperium, Reducing the Risk (Green-top Guideline No. 37a:

Thrombosis and Embolism during Pregnancy and the Puerperium, the Acute Management of (Green-top Guideline No. 37b)

Venous Thromboembolism and Hormonal Contraception (Green-top Guideline No. 40)

Venous Thromboembolism and Hormone Replacement Therapy (Green-top Guideline No. 19)

British Thoracic Society guidelines for the management of suspected acute pulmonary embolism
There are also some relevant international guidelines to consider
Current ACCP guidelines: