Can we play 2 singles matches in a “fourball tee time booking”

Yes this is permitted.

However, where possible we encourage two balls’ to aid with the speed of play. This is a guidance recommendation, not a competition rule or committee mandate.

Teams playing ‘2 matches on one tee time booking’ should be fully aware of the Rules of Golf, Rule 24.4-c

24.4.c A player must not ask for advice from or give advice to a member of his or her team playing on the course.

This applies whether the team member is playing in the same group as the player or in another group on the course.

Penalty for Breach of Rule 24.4: General Penalty. Loss of hole in match play

https://www.randa.org/Rog/2019/Rules/The-Rules-of-Golf/Rule-24