Williams, 32, said: "I want to be involved in the Six Nations and especially at Twickenham. I'm sure Warren will want me to play and I hope it will happen - I'll have 80 minutes to give a good account of myself.
"Of course, Warren has to see what kind of form players are in and he can't see that if you're on the bench. I don't like not being on the field and it was frustrating in France. But I'm a squad player and I've taken it on the chin.
"I've been out for six weeks and it's been difficult. It does not matter how fit you are, you need to get match fitness under your belt.
"I want to be involved on Saturday and show what I'm ready for. It's a massive game for us and I just hope we don't let ourselves down."
Williams was named in Gatland's 35-man squad, less than three weeks before the championship clash at Twickenham on February 6. And the British Lions star has hailed the shock inclusion of the next wing generation emerging from his region, 17-year-old schoolboy Tom Prydie and Kristian Phillips.
Williams added: "It's great for the lads and I'm really proud. I remember I said at the start of the season that I'd been training with two sharp youngsters and that was Tom and Kristian.
"They have worked really hard with their clubs and I hope they get a chance in the Six Nations. Hopefully they won't take my place on the wing just yet but they are good enough. They are massive talents for the future."
Wales have been boosted by news that Dwayne Peel could be fit for the second Six Nations tie against Scotland on February 13.
Scrum-half Peel limped off in Sale Sharks' European defeat at Cardiff last weekend but a scan revealed his groin strain was not as bad as first feared. Peel said: "Hopefully I should be back in full training in a couple of weeks."