If the steering is vague and heavy the tyres may be worn or under pressurised.
Rock the steering wheel gently while watching the front wheel, there should not be any noticeable delay between steering wheel and road wheel movement. Free play accompanied by a knock will fail the MOT test.
Check for wheel wobble at speed. This is often attributable to unbalanced front wheels. Steering wheel shimmy at low speeds indicated distorted wheel rims
Check the treads and side walls on all four tyres (plus spare wheel) there should be more than 2 mm of tread all over the tyre and the sidewalls should not be cracked or damaged.
Uneven wear on treads suggests steering, tracking or suspension problems.