It's a little way off, but many small landlords may well find the Governments plan to 'make tax digital' a bit of a surprise challenge. If your rental income is greater than £10k per year, then from April 2019 you'll need to do quarterly reporting to HMRC on a digital platform! 

It's been over 10 years since I sold my small rental portfolio and I remember the annual scramble to get all my tax information together. Hopefully there will be an app or platform that'll be up to the challenge.