Hello Jamesyboy! Many people simply take their car along and see whether it fails on anything. If the car does fail the MoT, then you have a week to make the repairs and replacements and then you can then take the car back for a free re-test. They will only check the repairs but if you take the car back after a week, then it must be completely re-tested again. In that case, you pay for a new test and they may fail it on something that passed first time.
There are many basic things like wipers, seat belts, lights, tyres etc that you can check. It's easier though just to run it along and see whether they fail it on anything. It may even sail through.
Hope that helps. Just keep your eye on the basic things over the course of the year.