You must leave a space after a punctuation mark. There must be some systematic defect in the Malaysian education system that makes almost everyone not realise this.
You also can't join multiple sentences with commas.
I, personally, would write out "Manchester United" the first time, and abbreviate it thereafter, but that would depend on the context.
"Farewell to Manchester United's legendary goalie, Van Der Sar. Best wishes for your retirement. May all the Man Utd's fans have wonderful memories of your contribution. We love you, VDS! Thank you for everything!
lyMan United fans" (I don't know what this line means)
"Best regards for you retirement" is wrong.
- For Teachers