I've not idea about Free Wills, but I do recommend everyone make a will. Its worth thinking about assigning power of attorney while your at it, not to be used now, but enacted at an appropriate point in the future.
I would argue that implementing a Financial Lasting Power of Attorney is more important than having a will.
Without a will intestacy rules automatically determine who gets what. If you have more than £270k in assets your Wife Husband gets only half of the remainder, the excess is divided equally between any children. That may not be the outcome you wanted, so get a will in place.
The reason you need a financial LPA is that if you fall ill or something happens to you that means you are unable to make decisions, your wife / husband doesn't automatically have the authority to make financial decisions or access any of their accounts or money or assets. This also applies to joint account holders, the bank can restrict you as you have no legal authority over your wife / husbands / joint account holders money.
It happened to Kate Garraway.
You should also get a Medical Power of Attorney, as without that you cannot make medical decisions on behalf of your loved one, or access their medical notes.
Not that it matters as much, in my experience Doctors do what they want to do anyway, despite you having a Medical Power of Attorney.