I’m going to give you all the background here because I had put a lot of this down before we spoke so a lot of it isn’t relevant but it explains why we are doing what we are doing.
If your father made a will but didn’t sign it, then it isn’t valid and there is not even any point in applying to court to have it admitted as a valid will. If he had made a previous will, then the previous will would still apply. Otherwise, he dies intestate and if your mother is no longer alive and you have no siblings, then you inherit the whole of his estate and his granddaughter and his girlfriend get nothing. Fortunately you agree with your siblings that GF and GD get the boat.
If he has no previous will, there is not yet any document confirming that you are entitled to deal with the estate until you have applied to court for Grant of Representation which enables you to deal with your late father’s affairs.
Here is the process: https://www.gov.uk/wills-probate-inheritance/if-the-person-didnt-leave-a-will
You are certainly going to need the Grant if your father left a house and any other property although depending on the value of the phone, transfer of ownership can sometimes be done with a Statutory Declaration that you are entitled to deal with the asset although they Grant is being applied for, the registration authority would insist on waiting till the Grant is in your hand.
Banks and building societies will allow a relative to deal with the estate of someone who is deceased by way of Statutory Declaration (if there is no land/property in the estate and the total estate is under £20,000 worth) without the need to apply for Grant of Representation . It is a simple form which all the banks and building societies have, which you take to a solicitor to have sworn for a fixed fee of 5 pounds. Pocket money for the solicitor because it takes two minutes.
Bear in mind that you may end up dealing with an idiot in the insurance company who has no experience of this. I suggest that you send them the following email.
“In reply to your request was some proof that I have been appointed Executor of my late father’s estate, I have to tell you that my father lived in rented accommodation and apart from the boat, probably worth about £5000, the only asset he left is about £1000 in cash. There is no need therefore to apply for Letters of Administration or Grant of Probate in respect of the Estate. I have discussed the matter with my siblings and we have agreed that I should deal with the estate. You can therefore take this letter as proof of that or if you wish, if you let me have a draft statutory declaration confirming that I am responsible for dealing the estate, and which would satisfy your requirements I will get that sworn by a solicitor and returned to you. If that is not sufficient for your needs, perhaps you could tell me what you actually need because having taken legal advice, that is the only option other than applying for Letters/Grant which is simply not necessary in these circumstances. If you are not prepared to come up with an alternative, then there would be no option but to cancel the insurance and arrange it elsewhere.
Yours et cetera”
On a completely different note and something that you haven’t asked about but if there is enough cash for the funeral, do remember that whoever arranges it is responsible for paying for it and if you don’t have enough money to pay for it, then you need to contact the local authority (the funeral director will help you) because you can get assistance from the local authority to pay for a most basic disposal. However it’s essential that you work with the funeral director and the local authority in those circumstances so that you don’t end up being stuck with the bill if you are the one who made the arrangements.