Sorry but this is a bit naive.
1. If the area is highly desirable and you can rent out the property easily for 500/month, you can forget about the 80K pricetag.
2. You're completely ignoring rental income tax.
You must normally pay income tax on any profit from renting out property you own. Put simply, your profit is the sum left once you’ve added together your rental income and deducted any allowable expenses or allowances.
Your rental profits are taxed at the same rates as income you receive from your business or employment – 20%, 40% or 45%, depending on which tax band the income falls into.
Btw: you can't deduct your mortgage as an expense, only the interest on it.
You pay 8 * 255 * 12 / year on mortgages = 24480.
You collect 8 * 500 * 12 / year in rents = 48960.
You pay 40% taxes on your collected rent (higher rate tax band) = 19584.
Congratulations you make 408 per month ((48960 - 24480 - 19584) / 12).
So even if your house prices and renting numbers were right (and trust me, they are not), you would be living in absolute poverty for at least the next 25 years.
3. If you think managing 8 properties is "retirement", think again. Finding tenants, collecting rent and property maintenance is a huge pain in the ass.
Your numbers are off, you are ignoring important costs and underestimating the actual work involved.