http://www.whichwills.com/
Have a look here - trusted organisation, reasonable price.
Although you can do it yourself
This is my last will and testament.
I,...................., being of sound mind and body will my estate, property and all assets in its entirety and without hindrance to be sold and the proceeds to be divided equally for the benefit of my children, (name here) and (name here).
I nominate (child one) and (child two) as executors.
Signed................................ Dated.................
Witnessed by ...............(not children) and ..............................
addresses here............................... .....................................
Date ...................... ....................................
If anyone can pick any flaws in that I'd appreciate comments.