That is my theory. Use the £50k or so equity that we have in our Bungalow, which has resulted from 3 years of working our fingers to the bone with the renovation to put towards buying a Terrace in the city.
Then, go through it, spruce it up simply and rent it out.
As others have said, the rent earned from it might result in only breaking even, or maybe even a negative scenario, but the alternative is to pay £200 or whatever into a pension. At least the house will certainly be worth more in 30 years than it is now, by which time the mortgage will be paid off. If things work out well, the Terrace might actually jump up in value then we are in a good position.
Matt, when you grow up a little and get out there into the real world, you will see that it's not that easy. Money is tight for us, but we aren't on the breadline. However, I'm not getting any younger and you have to make plans, even if that means spending a bit of money.
If this outcome was obvious, I wouldn't have asked the question in the first place, but as I can see that the figures are a juggle and that there is a good chance that the mortgage would equate to the same or more than the rent/upkeep, I wanted to make sure I hadn't missed anything obvious.