Dunstable is about fifteen minutes from Wigmore across the A505, so there is no call-out charge in Dunstable or Houghton Regis. Same in Toddington, Caddington and Kensworth.
Remote first where it works, on-site where it does not — and for workshop and yard problems it usually does not, because the answer depends on the building. Anything involving cable, an access point or a machine that will not power on needs someone there.
Everything is diagnosed before parts are ordered. That matters more here than most places, because a machine that looks dead in a dusty unit is very often just hot, and the difference between those two conclusions is about £150.
For a trade business the sensible first job is boring and worth it: a list of what you have, a working backup of the one machine that matters, and the network sorted so the office and the unit are on the same side of it.