I've always used my hiking/mountaneering stuff when cycling and it has done great, but I'm now going out more often than the washing can't keep up with so need to buy some more clothing and figure it may as well be proper cycling stuff.

So what goes with what? Do you wear a baselayer under everything? Even if it's hot and you've got a jersey on? When it's colder and you've wearing a softshell type item, do you wear base layer -> jersey -> shell, or just base layer -> shell?

I'm looking to buy suitable clothing to get me through the rest of the spring and Englands wonderfully unpredictable summer. What type of combinations should I be looking at getting?