Been years since I paid for a setup, get yourself a decent notched straight edge (I have a Crimson one which does all common bass scale lengths, not cheap though) and some basic tools then watch a ton of luthier videos on YouTube. £125 is a lot for a basic setup and nut adjustment, unless you also need a fret dress then I'd look elsewhere.
The last four basses I bought all had wholly unsuitable setups for me, one needed a fair bit of adjustment and two of them needed frets knocking down higher up the board, the tools have paid for themselves already.