Just wobble the steering wheel side to side Dave. Small movements each way and watch the front wheel for movement. If you want to check the vertical movement on the centre of the rack. you can twist the steering column with the offside bonnet up, and see what happens. It shouldn't be a problem with cars as new as ours, and the tester didn't bother about it. Apparently new/young testers are being told to make allowances for 'the life/age of components', and accept that things wear over time - eg kingpin bushes. The wear on my nearside is clear, and disappointing given the mileage is still under 10k. But looking on the bright side, it means that I can justify some hard chrome kingpins, and a Mulfab roller bearing conversion over winter, which will make a really good thread.
I only resolved to look at the rack adjustment because I don't like things that are not 'right'..... but I had to wait for the spanner to arrive. It seemed worse when the engine was hot, so thermal expansion of the rack housing may have played a part.