While I do not see a problem with buying using bitcoin I think rental is more difficult. If a property was being rented at £800 per month or 0.2 bitcoin at time of agreement then if price of bitcoin increases then tenant will have to pay more using the same amount of bitcoin. A tenant could not be sure how much in £'s they would be paying monthly.
You can add a clause to the agreement stating that, for example, rent is due at the 1st of the month. You can agree on a timestamp, say 12AM each 1st of the month. Then calculate the BTC due for the month according to it's value in fiat at that timestamp.
Of course you can say there's risk involved because the value can increase or decrease, but as a tenant, you shouldn't be spending your BTC if you want to use them as an investment. And the landlord shouldn't hesitate and convert BTC to fiat if they don't want to risk losing money that month. If everything is worked out properly in an agreement, this thing could easily work.