what is the safe and cheapest way to transfer money from nepal to uk ? I have contacted with few agencies but they require huge amt of commision in different way . Please help me soon.

 Hundi. Not a legal way of doing things but it is really cheap. How much are you looking to send? I've got some friends in London. Maybe you could sort it between yourself. 

I need to send 5lakh . How can I send it through with your friends and whats the charges ?? I need to send it by 2-3 days. urgent.

huge commission??? it's called transfer fee. Imagine that fee if you had to travel yourself and hand it over. Just think about it if you are freaked out that they're asking for too much money.
I don't know what's the law in your state, here in california, You can't send more than 5,000 a day and if you try to send more than 2000 to UK, you'll be asked tons of questions, in order to save you from possible frauds/scams being played around from those countries.
Go for western union , money gram sucks

 Man..that's like a huge sum..let me ask my buddy... 

I have contacted gurkha money transfer and they told me that they can transfer required amount to bank a/c of london. As I talked with them this morning they told me that , They will transfer 5lakh for 1 Pound=Rs 125. Isnt it high ?? I need your guidence buddies.