The government sets a maximum MOT fee of £54.85 for a normal car, and garages are free to charge less than that. That is why prices vary from street to street even though the test itself is identical everywhere.
Anything on top of that price is repair work, not the test. A good garage will always separate the two on your bill so you can see what you are paying for.
You can read what the test covers on our MOT testing page, and see our current from-prices alongside servicing and tyres on the pricing page.
Watch out for very cheap headline offers that only apply if you have the repairs done at the same garage. We do not work that way.