Depends on how much oats you decide to use, really. Kaptain Karma's method will work nicely. He's right - you will need to conduct at least a partial mash.
you really don't start impacting mouthfeel until you get to around 5% of the grist. After that it becomes really noticeable.
I like malted oats more than flaked or Golden Naked. You can get oat malt from any retailer who has access to Thos. Fawcett's products. There's a lot of husk material, so you don't have to worry about sparging, and it's malted, so you can just do a partial mash of 2 pounds or so of the oats alone. Still, as long as I've got the tun heated up, I mash mine with at least 2 pounds of 2-row.
In fact, I've been meaning to try oat malt in a bitter or something for some time. Perhaps this Spring (in my copious spare time!).
Cheers,
Bob