Heat beads are generally thought of as one of the best quality briquettes you can get in the uk, exceeding or equal to the long life weber stuff. They can take a bit longer to light, but they also have a long burn time, as for heat it's down to how well you regulate the fire, they can burn nice and hot if you give them enough air. Only downside is they're quite pricey, but then so is the weber coal.
A lot of people (including myself) use restaurant grade lump wood charcoal, you can buy big blue bags of it from makro/bookers quite cheaply, Big K also sell some very good coal which is very high quality, the RCH12 & RCH15 -
http://www.bigkproducts.co.uk/Catalog-B ... al_29.aspxLump wood will burn hotter than briquettes and doesn't have any of the binders used to form them, so no additives whatsoever, 100% pure charcoal. The cons are that it doesn't burn quite as long as the high quality briquettes, and doesn't burn as evenly, so the temperature can fluctuate a little. But as long as you know your pit and can manage a fire then it's perfectly fine for low n slow cooks, a full ring of lump wood in my wsm would easily burn for 15-16 hours.
In theory if you wanted to use the most appropriate fuel for each situation then it'd be briquettes for smoking due to more even burning, and lump for grilling due to higher temperatures. But a good quality fuel of either type will do both happily.