It's all going to his widow. The probate helpline is sponsored by a company that has quoted a fee of 2% of the estate. Sounds pointless to me. Surely he doesn't need to use a firm? Has anyone found them helpful?
There are two steps to probate - one is filing the Inheritance Tax forms with HMRC and the other is applying for probate. It's the tax bit (if it applies) that is really the complicated thing rather than applying for probate but you can't apply for probate until the tax (if there is any to pay) is paid. Many estates (low value or whole going to spouse) won't have any tax to pay anyway.
It is worth using a solicitor (I don't know what you mean by a probate company exactly but you want a solicitor specialisted in inheritance and probate if you need help) if the value of the estate means that there is or could be tax to pay or if you need to apply for allowances (eg. a deceased parent gets an allowance in respect of the family home if left to a child but you need to apply for it).
If it's all going to a spouse it's probable that there won't be any tax to pay depending on whats in the estate, the value of it and if there are other bequests.
Then once you've got probate, it's just about calling in all the assets (ie. selling ISAs or stocks or shares or property) or just transferring them to the name of the beneficiary if that is what they want. If there is a lot of individual assets (lots of stocks and shares, bank accounts and so in) it will be time consuming admin but its all doable by yourself.
It is possible also to negotiate with a solicitors firm anyway and agree the charges and what you want them to do. So you could say
I just want you to advice me on tax, fill in the tax forms and fill in the probate applications - I'll provide all the financial info, I am not prepared to pay a % of the estate as this is a small job. Can we agree a fixed fee or an hourly rate? Shop around if you decide you need lawyers.
From what you say, if it's a small estate, all going to the spouse and you've got the time/energy to do it, you could do it yourself.