1) Follow the recommendations and discussions that have taken place for Mike941. I assume you've already done this if you're posting here.
2) As discussed earlier, you can get a large majority of the dust out of your heatsink with a blast from a can-o-air. This method is nearly fool-proof and should always be attempted before disassembly. The severity of the buildup somewhat dictates the best approach. For light dust, just point the air nozzle into the fan (intake). Short bursts so the fan doesn't spin too fast. Better that the fan doesn't spin at all, but you can't always get something in there to keep it stationary. After that, you could do a shot into the exhaust vent to loosen things up, followed by a shot in the intake to push the remainder out. For medium-heavy dust buildup you may need to insert toothpicks/etc to get things completely loose. If it's really plugged up and sticky, you'd probably have to resort to disassembly. Again, that's last resort.
3) A person that knows very little about computers but is skilled at tinkering/taking things apart/fixing things should still be able top open up a laptop to get at the cooling fan (if needed, see #2). There are many "disassembly" videos on YouTube. You can look up a video for your specific model or a smilar one. Just make sure you keep track of where all the little screws belong and don't force anything unless you know you're doing it right (top and bottom halves are held by plastic clips around the perimeter after all necessary screws are removed for example). Refer to youtube videos and TR forums for help if you run into a "snag."
4) Re-applying TIM is not worthwhile in most cases (IMO).
5) It's best to periodically clear the dust from your heatsink/fan using step 2 rather than letting things build up to the point of step 3. Keeps your laptop cool, quiet, and happy.
Main: i5-3570K, ASRock Z77 Pro4-M, Asus GTX660 TOP, 500GB Crucial BX100, 2 TB Samsung EcoGreen F4, 16GB 1600MHz G.Skill @1.25V, Silverstone PS07B
HTPC: A8-5600K, MSI FM2-A75IA-E53, 4TB Seagate SSHD, 8GB 1866MHz G.Skill, Hand-Built Wood Case