The conditions are good and dry. You could use the ‘two-second rule’

Explanation: To measure this, choose a fixed reference point such as a bridge, sign or tree. When the vehicle ahead passes the object, say to yourself 'Only a fool breaks the two-second rule.' If you reach the object before you finish saying this, you're TOO CLOSE.

Category: Attitude

References: The Official DVSA Guide to Driving: Section 7, The Official DVSA Guide to Driving: Section 10, The Official DVSA Guide to Driving: Section 11, Highway Code: Rule 126