I was in the same situation back in the summer - elderly relative on EOL care just before a family cruise holiday (which would have been extremely difficult to leave part way). In the end, she died exactly a week before we were due to leave.
Yes to having funeral arrangements up your sleeve. At the very least, have the number to hand of whichever one you choose; obviously you can do your research now. They can swing into action as soon as the death is certified.
My relative died at about 5am on the Tuesday in a nursing home and was certified by a doctor within an hour. I called the funeral director's out of hours line at about 7.30am and they arranged for the body to be collected that morning and taken to the mortuary. The FD themselves called me back at about 9.30 and I was in their premises making arrangements before lunch. That bit was easy.
Registering the death was the big issue. This will be an 'expected' death in legal terms so the medical professional who certifies the death will inform your local Medical Examiner who will then review it. It is unlikely they will throw up any problems, but it could still take two or three days for them to contact you once they're satisfied about the cause of death. Once the Medical Examiner has contacted you they will inform the Registrar themselves and you then have five days to register the death. In our case the Medical Examiner didn't call me until the Thursday morning and we were due to leave on the following Tuesday; fortunately the registrar had an appointment available on the Friday morning. I had told the ME about our holiday plans when asking about the timeline for the process and he did pass that on to the Registrar, which helped greatly.
Registering the death is supposed to be done by a close family member, but I can't see why a solicitor shouldn't be able to on your behalf if you can't make the timescale. As PPs have said get the right documentation together in advance. I've copied and pasted below the email I got from the Registrar confirming the appointment, to give you some idea of how you can prepare:
Dear CaptainsLog
This is to confirm your appointment to register the death of your elderly relative on Friday 01 August 2025 at 10:20 at Salford Register Office.
You will be able to request and purchase certified copies of the death certificate during your appointment. The cost is £12.50 for each copy. You can request multiple copies at the time of registration and the Registrar will talk you through how many you may require.
Please note that after registration, additional copies may be ordered via our website.
To help us record the correct information on the registration, please bring with you documentation relating to the deceased such as; Passport or Driving Licence if you have access to them and documentation for yourself such as Driving Licence, Council Tax Bill or Recent Utility Bill.
Please note that any mistakes found on the death certificates after registration will incur correction fees of up to £99.00, we will ask you to check the register page carefully before signing and any mistakes found at this point can be rectified in your appointment.
Please ensure you arrive at least ten minutes before your appointed time. If you are not able to make your appointment, please contact us as soon as possible to rearrange your appointment.
The other thing I would strongly suggest you do as quickly as possible is use the "Tell us once" service as soon as the Registrar gives you the code. Twice in the last 18 months I've had situations where pensions/benefits payments have been made after the death and had to be paid back. The quicker you use Tell us once the less this becomes an issue.
If you can make the arrangements work, go on the holiday. My relative was 95 and had been in really poor health for a long time. I feel no guilt about the relief when she finally did shuffle off, and none about having made detailed plans in advance.