You should register the death abroad, according to the regulations of the country. The British consulate will have to be notified if a death happens abroad so that they can issue a consulate death certificate. This is required in order to record the death in the UK.
When someone dies abroad, the process of repatriating their body can be complicated. The first step is to contact the embassy or consulate of the country where they died. They will be able to provide you with information on how to proceed with repatriation.
The next step is to contact a funeral director in your home country who will take care of all the necessary arrangements for repatriation and cremation. You may need to pay for these services upfront, but they should be reimbursed by your insurance company if you have one.