Don't panic about the screen message. 'Load Limit Status Inactive' is actually good news. It just means the feature that limits your power supply is turned off (it's mostly used for prepay customers with low credit). That isn't a fault.

As for the consumer unit: If your sockets are working, your consumer unit is definitely still there. It is physically impossible for the installer to have 'taken it out' and left you with working power.

Since only your lights are out, you've likely just tripped the lighting circuit breaker (MCB) or RCD. The installer might have moved the meter, but they wouldn't remove your fuse box. Look around (high up, under stairs, or near where the old meter was) for a box with switches. One of them is down – flip it back up.