The hotels around Team Valley aren’t a bad shout actually. It’s a massive industrial estate, so parking isn’t really an issue and no one is likely to kick up a fuss. They’d be unlikely to notice… It is however 2 or 3 miles to ride into town…
There’s some ropey areas you could park closer for free. Depends what kind of car you drive and how much you value it 🙂 (edit: see lemonysam’s suggestion….can be difficult getting a space during the day though)
Or there’s some secure car parks dotted around the city centre, some with 24 hour security. Depends how much you want to pay? The city centre isn’t an easy place to park without paying tbh.