There's plenty of on street parking if you know where to look, but you are better parking on the surface car parks on Winwick Street. Usually a couple of quid but I think the robbing gets put it up to £4 on match days.
If you want somewhere free. Total Fitness shut down last week and may be available.
Get to Orford Lane and park down the side of The Hawthorne pub, parked there for years, if thats full there is another car park further up, just outside Donatello's itallian. FOC.