Beware of the costs ripped out of an estate by a solicitor as an Executor, and that they are in no hurry to do it, or interested in getting your estate to your beneficiaries. Ditto if you use an Accountant as Executor. If there is any complexity the solicitors are very quick to bring in an expensive tax accountant.
If trusts and schemes are involved it can be a bit mind-boggling understanding the HMRC rules. HMRC tend to prefer folk to use a tax accountant, makes it easier for them and more likely to be right. If HMRC have to do the checking/donkey work of a non-specialist submission, they are alledgedly harder on the case and liabilities.
Certainly name several executors, sometimes they decline to do it after you're dead. It can then be very difficult, if at all to get, to get new ones appointed. Cannot recall, but I suspect, named beneficiaries cannot be elected as the new executors by the courts.
A "dead file" say on a secure memory stick, is a very useful thing for executors. Listing all assets, bank account details, insurance and other policies, pass codes, where paper docs are located, scanned copies thereof on the stick (birth certs etc), location of deeds. Someone trustworthy needs to know where this is of course. It might be wise to have two, so there is a check on anything claimed by a suspect executor.
Also check on what organisations need from an estate in order to release funds or documents, this can be a real sticking point. Some view this as a device to extract more money from the estate viz:.
Halifax retain a £1 charge on an estate when the mortgage is fully paid off (save the £1) when they hold the deeds for safe keeping. They then charge for a Halifax building insurance policy, on the grounds that it is safeguarding their (£1) interest in the property. It is billed to the dead estate, who cannot pay it until probate is granted, which can take years. In the meantime they charge interest on the unpaid bill. The Deeds dept then demand an original, not a copy, of the death certificate, which curiously keeps getting lost. In this way they can accumulate a substantial claim for unpaid debt and interest. Further, they then refuse to release the deeds to enable the property to be sold until they have been paid first.
It is often the case that the Executor has to have funds of their own to make it all happen, and eventually are able to reclaim their expenses from the estate, often over a year or more later. Solicitors and Accountants, if they fund this, add an interest charge (at what rate???).
There are firms who are set up purely perform the executor role, some are questionable, others are by honest people who have been stung like this themselves. I might use one of these myself.
Whoever you go to, do the detailed research, check references, nail down the rates, charges and time scales etc. first, in writing. Certain stages have an open timing, e.g. grant of probate request should be submitted within a given time, but award of same can vary. Tax submissions and replies can be determined with a max/min time envelope, ditto other actions (get or do a list of the stages/actions, find it ponline then tailor it to your estate - put it on the death file, the Executors/beneficiaries will thank you posthumously).