There's not really a distinction, domination doesn't have to incorporate any S&M factors at all. If you're not into pain play, or only like spanking, or just like it light as more sensation than outright pain, or want to full-on flay your partner til they bleed, it doesn't change the sub/Dom dynamic. That's why it's important to discuss limits before getting into anythign with someone, because it's impossible to just know by what label they use. As long as there's an element of control, it counts, whether or not it incorporates S&M, sex, punishments, or whatever.
Hard to give ideas without knowing specifics of what you'd be into, but in general looking at the Bondage Boutique range is quite good - http://www.lovehoney.co.uk/brands/bondage-boutique/ - and there's even a special offer on them at the mo, free bondage tape with every £25+ you spend, which ain't bad.
In general, I'd say best staples are restraints of some kind (the tape is easiest/cheapest), a blindfold like http://www.lovehoney.co.uk/product.cfm?p=15716 and some sensory play devices like http://www.lovehoney.co.uk/product.cfm?p=15808 and http://www.lovehoney.co.uk/product.cfm?p=16483 Depending on how far you want to take it, looking at collars, cuffs, candles, floggers and paddles, nipple clamps, and so forth are good, but would need more information (eg for collars, would need to know rough dimensions of your neck so it can fit right). There is a good basic bundle on the cheap: http://www.lovehoney.co.uk/product.cfm?p=19289
Also, remember that she'll feel more in the part if she's dressed up, so things like thigh-high boots http://www.lovehoney.co.uk/product.cfm?p=12152 and playsuits or vests or something like http://www.lovehoney.co.uk/product.cfm?p=13295 will help her feel sexy (and especially if she's semi-clothed while you're naked, that'll have it's own element of power play).
And hi! :)