Making a Will without paying over the odds

Bubblette_2

I would like to make a Will now to avoid confusions if I did pop off early. I want to leave everything to someone who is now a baby, so would like everything to be put in trust until he is 21 if I die before then. So would I need to pay a financial advisor to find out about a trust that would ensure he would get a good return when 21 AND a solicitor to draw up the will properly? I've heard that you can write a will yourself and just get two people to witness your signature, but I want to be sure that it's all done properly (including alternatives if - heaven forbid - the baby died before me). Also, if I wanted to change the will, do I have to pay the same fees again?

It's all quite morbid this! But I want it straightened out - is there any way for someone who's not sure about legal things to get this done cheaply??

Thanks