If Southend has full ATC ( like at Coventry),what you are actually paying is the 'approach fee'.If you initiate a go around from finals,then you will get billed as though you had landed
.Same applies to t&g's.If ATC order a go around,then you don't pay.
I have never really thought about where the actual point in the approach is where you actually become financially involved,will try to remember to speak to the tower next time I am there.
MM