welcome to the forum and epic in general

if you're learning the game, I can recommend the training scenarios in the rulebook which will introduce you to the mechanics of the game and help illustrate the different rules concepts
I'd also recommend starting off painting up your orks and IG forces to learn the game with, marines are a little more fiddly, and eldar fiddlier still (with a tonne of additional special rules to boot) by all means try them out, but if you're learning the game, probably best to leave a full sized game with eldar until you've got the hang of engagements and the air rules!
it's probably best to start small for your first few games, 2k is a decent size, it's also probably best to avoid using aircraft at first, and try not to max-out on the war engines as they add a bit of complexity and fiddliness
As Ryan said, if you're UK-based, we'd love to see you guys at an event sometime, they're super friendly and beginners are always welcome
