Rather than attempt to re-write some of the excellent existing resources provided by Cycling UK, I will link to the most useful bits.
Are there are pre-emptive measures I can take?
Cycling UK membership includes free legal advice on cycle-related matters, including following a road traffic collision. Membership also includes third party insurance in the event of claims for accidental damage made against you or your cycle.
What to do if you’ve been involved in road collision
You can find detailed and practical advice on what to do in the event of a cycle road collision courtesy of the Cycling UK’s Road Justice campaign here.
Contact the Incident Line even if you are not a Cycling UK member as legal advice may still be available, though on different terms to those available to Cycling UK members.
What to do if you’ve crashed on tram lines
You can report tram crashes via tramcrash.co.uk. CycleSheffield are collecting this information to help us understand how common these types of crashes are and where they happen.
Why it is SO IMPORTANT to report your collision to the police
The police have a duty to accept reports of all road collisions which result in an injury (even if minor). This includes single vehicle incidents. Even if the case is not pursued, the police must record details of the collision by filling in something called a STATS 19 form. The data collected via STATS 19 is lumped together, anonymised and published annually. It is used by local authorities to identify the roads where the most collisions take place, and which should qualify for safety improvements.
If you do not report your collision then this data does not reflect a true picture of cycle collisions on our roads.