Oh man, that clicking sound is the worst! My old rig made that exact noise right before it basically died mid-game, totally ruined my night. Since you are in the UK and have a 100 quid budget, you have to check out the Corsair RM750e 750W 80+ Gold Fully Modular. I picked one up last year during a sale and its been absolutely fantastic! It is fully modular which makes cable management so much easier for a beginner, and honestly, the silence is amazing compared to my loud old unit. Its super reliable and definitely fits right in your price range if you shop around a bit. Just make sure you grab it while it is on sale, you will love it!