The investors that I am talking with right now are looking to maximise on incentives that builders are offering on New Construction. 

We’re considering loft conversions/extensions to maximise the capital gain.

You can maximise cash flow and still have multiple exits. 

We will gladly let someone else give them the money (and in some instances buy it as a NPL later on for a discount) I can tell you, any serious borrower counts the ROE and IRR, and definitely utilizes leverage to maximise those numbers.

If your intention in investing is to maximise your returns inform your tenant that they are below market and that you will be raisin rent 400/month in 60 days.

Leverage investors seek to maximise income on their investments forcing their money to earn it's keep. 

Tenant and SFH resale do not go hand in hand.Your best option is to set it up now for tenants as I suggest and then do another reno to upgrade for sale.....possibly stone, hardwood and tile to maximise profits when you sell assuming they are appropriate for your market.

If it can not be pulled you will need to sell to maximise those returns.

First you must realise that the purpose of investing is to maximise your income.

All you are doing is saving that interest payment which means you will never be able to maximise your returns and achieve a descent return on your money.