Janey's point about needing to have decent equipment is a good one. If you do get it done somewhere else, then they should be able to give you a printout of how they've set your car up, then I'm sure you'd be able to ask Tony to double-check that it's indeed correct.
If you can make the trip to WIM, you won't regret it, they've very professional. But I realise it's quite some way. However, other LOC members have travelled a lot farther just for a WIM visit, they thought it was that worthwhile !