There are plenty of "rattlecan" tutorials out there although you'll find that Halfords paint runs high in solvents, so the last half of the can shoot more solvents into your paint than you'd prefer. This causes all the nasties, like solvent pop and all that. You'll need to grainfill your wood (go to behlen.co.uk) before you start else everything will just sink into the wood. If you make sure your wood has been sanded through from 80 to 400 grit before you start finishing you should be okay. The yellow primer filler is a good start as it's pretty high build. One thin dusting "sealer" coat works well if you shoot it from a couple of feet. You're not aiming to obscure the piece in one coat. Plenty of thin coats are your best friends :-) A few coats of the yellow filler left to dry can be wet sanded back with 320 grit till you're left with a nice uniform smooth surface. If you're using a sanding block, spray a light dusting coat of a contrasting colour (black?) from a few feet back - when you sand the surface flat, dips reveal themselves as unsanded patches, and high points as the first places to reveal the lower layer or as patches with circles of the highlighting colour around them.
Plenty of patience and lots of paint work wonders! You'll end up cutting back a lot of primer if your initial sanding work wasn't up to scratch, but once you're at a smooth as satin 320 grit surface, you should prime a couple of times with white, grey or red (whichever the final Halfords colour recommends) and slowly apply thin coats of your colour allowing plenty of time to cure. Cutting back with 600 grit wet and dry between coats works well for me.
Solid colours don't necessarily require a clear coat. Metallics and Pearlescents however, do. I would allow several more coats of a solid colour in lieu of a clearcoat.
You might also find that if you're using (not wasting?) the last 50% of your cans, they can spit paint into your finish which needs to be cut back. Don't hang your finger over the nozzle either! If you have a colourful finger, you could end up causing spits in your paint from your finger disrupting the paint stream. When you start spraying, spray "before" the piece before moving into the area you want to spray. Equally, release the nozzle after you "overshoot" the piece. Paint can spit when you start/stop spraying.
I'm not expert - these are blahs from experience in minor car repairs, a couple of body finishes and what I've read. Choose your information and I hope it helps!
Oh yes, there is never any harm in letting coats cure too long but plenty of harm in shooting new paint when it's partially cured. Keep some clean cloth rags handy and remove any dust that might have settled on your piece whilst curing.
If you're able to, dampen the floor of the painting room so any overspray paint dust doesn't get circulated into the air and contaminate your work. Clean is awesome.