You might not need landlord insurance but you absolutely need property liability insurance which usually comes as part of the package. If you do not have that and have risked it then if the tenant is injured in your property by fire, faulty wiring, carbon monoxide etc for example then you are opening yourself up to a lawsuit.
You have to let your mortgage lender know or you may invalidate your mortgage/buildings insurance. You also have to let them know if the property is empty longer than 30 days (can happen in between tenants).
You have to have an annual gas check - letting agent usually organises.
You have to to have deposit in proper tenancy deposit scheme - letting agent will organise. If not you lay yourself open to losing it automatically/legal action.
I personally would install carbon monoxide monitors -quite cheap to do, as well as smoke alarms.
You have to work out in advance the tax agreements between UK and where you are moving to...tax exemption form needs to be filled out in advance or it will be taken by agent at source.
I would rent unfurnished as then you are not liable for maintenance of fittings and furnishings and their safety as mentioned above. You will need to offer cooker, decent heating and a fridge is usual (although I did not leave the latter, but I did leave vaccuum and mower and gave them to first set of tenants to keep so again not responsible for replacement).
You would be advised for landlord's insurance if you are relying on the rent to break even with the mortgage -the rental figure must be 125% on your usual monthly payment. The bank usually has to convert to a buy to let, standard variable or adding a per cent on as a load if you are renting out. You can choose not to tell them but that would be really unwise. Be aware they can be arses wrt tenants on housing benefit - some banks insist on no students, no DHSS, no pets etc Others sometimes accept a guarantor for your tenant.
WRT 'bad' tenants that will end up in court anyway irrespective of the insurance - added legal will help but won't stop tenants outstaying notice as long as the council refuses to offer help until they are evicted (otherwise the poor buggers are deemed to have made themselves intentionally homeless): also there are excesses on things like malicious damage BUT insurance packages are brilliant when it comes to things like burst pipes...they will cover the tenant in hotels during repairs (whilst they continue to pay your rent) OR if you lose the tenant due to flood then they will pay your rent to you and the tenant is released from the contract. So you don't have the property being repaired for months whilst paying the mortgage as well as your current rental (we ae not professional landlords either and in 7 years have always broken even or made a loss but wanted to be able to come back if needed with 3 months notice to tenant obv.) Be aware of the complex rules of capital gains tax if you should decide to sell after all while you are away or if you come back (you will need to check the details with gov. online as I am hazy).
Finally accept your house is no longer your home and may get trashed, flooded etc Channel Elsa and Let.It.Go.
Accept you may have periods without a tenant and no rent coming in or that you have multiple tenants and have to pay the agent each time.
Accept the agent will be charging a percentage plus VAT simply for being there so you don't have to...so make sure it is someone you trust who knows their stuff.
Have done it for 7 years, same agent, 1x left in shocking state/deposits company upheld in our favour, 1x burst pipes (make sure yours are lagged or tenant agrees on ambient temp even if away but hard to enforce or prove).Our insurance paid for damage and loss of rent (tenant wanted out rather than hotel, fair enough). Have had 5 tenants in 7 years so 1250 quid in additional fees for vetting/contacts etc BUT my agent is bloody brilliant (pm me if you are in the North West).
Good Luck xxx