Unlikely to need stilsons for first few jobs
Brain
Flexible arms
Strong, bendy fingers
etc
Pencil
Spirit Level
Measuring tape
Decent adjustable spanners
Decent pump pliers
Pipe cutters, 10mm, 15mm, 22mm, 28mm
Cordless drill
Electric drill
Screwdrivers
Stanley knife
Another pencil because you've lost the first one
Towels
Kitchen roll/blue roll
Pressure gauge
Bicycle pump
Hammer
Another flamin' pencil cos you've lost another
Pen
Smaller spirit level
Larger spirit level
Junior hacksaw
Circular saw or Multi PMF 180E
Another pencil cos the customer's puppy nicked the one you were just using
Saw
Another saw - one for cutting plastic pipe, one for wood
Torch
Gorilla bar
Chisels
PTFE tape
Loctite 55
La-Co Slictite
Working lamp
Multimeter
Wire wool
Flux
Solder
Blowtorch
Flux brush
Rag
Radiator keys
I got carried away here but most of these tools are used at least once a month - there are other threads covering this.