The TES Resources section is probably the largest collection of user-contributed free teaching resources in the UK. Registration is required and a subscription service is now in place, but the basic resource library service is still free to use.
The TES Forums host fervent discussion on teaching and curriculum related topics.
The TES Jobs section is widely used by UK and International schools to advertise teaching and education related posts.
Front page of the TES site
Probably the busiest online discussion forum for teachers in the UK.
A massive collection of teaching resources created and shared by thousands of teachers
The largest collection of teaching and educational job advertisements in the UK.