Just spoken to my DS, who is a really keen driving gamer. He only knows of 2 games where you can free roam, The Crew and Grand Theft Auto GTA, but you can't use a wheel with GTA.
As for the wheel & pedals, it all depends on your budget.
Have a look on Amazon/Argos, an entry level wheel such as the thrustmaster t80, will cost you around £100-110. These wheels are ok, but they are not brilliant, they are nowhere near as responsive as the more expensive wheels.
Me and my DH have a Logitech G29 wheel, which is currently £199, it's much better than the t80. We are both early 50's and still love driving games.
Which ever wheel you buy I would recommend a stand to bolt it onto, such as the GT omega, which is £110. You can attach them to a table but the stand is miles better, it makes it really solid.
Be aware it can become very expensive, our son started out with the t80 wheel but now he has got a very expensive steering wheel set up, with a full stand including sliding seat and a £500 wheel.
The best driving games in my opinion are Gran Turismo, Project Cars and WRC, but none of these games are free roaming.