Your Dad is looking backwards, you need to look forwards.
When I bought my first few properties, moving was resonably cheap (and property was rising in value - although it did stop for 5-7 years after 1989) with no or little stamp duty and no mortgage fees. Now its different.
Interest rates are 0.5%, but mortgage rates at plus 3% - so if interest rates slowly move up to 5%, that will put mortgage rates at nearly 8% - more than doubling your payments.
Interest only is useful when you need a break, e.g unemployment, first child - and depending on how young you are no problem for a few years.
I wouldn't be worried about paying off your mortgage early, as long as you've a plan to actually pay it off.
Don't buy too small, and don't buy something you can't afford to keep.
When we came back from working abroad we (2 adults + 1 child) decided that we need a house for the next 10 plus years that could be afforded on one wage, while still having a life. So we bought a nearly new 3 bed deteched. We still live there. And yes at the time we would have easily got a mortgage for a 4 bed, and there have been times in the past 10 years when our mortgage was less than one multiple of salary.
We still live here, and TBH I can't see us moving - well not for a while anyway as we have a 0.3% above base-rate tracker 
