You will easily find second hand pianos. It's worth finding someone you know who plays the piano to assess whether you are getting something that should be consigned to the scrapheap.
You can't tune them yourself without training and tuning wrenches (You need more than one). It's hard to do as once you get out of the deep bass notes you are looking at two or three strings that have to be tuned harmonically to produce a single tone. The strings are also under enormous tension - you really don't want to snap one. You usually pay a professional piano tuner to do it. It costs upwards of £60 depending on where you are in the country. They only need tuning maybe every 3 years or longer if they are kept in a normal heated room. Mine needs doing, but hasn't been tuned for 5 years.
The hard bit is getting the piano transported to your house. They are very heavy. Digital pianos are really good now, but they never have the action or character of a real piano..
This.
Some pianos go out of tune by the next day, some (generally the better ones) will go for some time. In fact the piano I've got here in France was last tuned about 30 years ago in Devon, has been in three different houses, and been transported 850 miles in a car trailer to get here. It does need tuning now. And it's definitely a job for a pro - I learnt to tune my harpsichord, as essentially they need tuning/tweaking every few days, but the temperament I used is much easier to do than equal temperament (that pianos are tuned to), and the mechanics also much simpler.
Obviously they are much nicer pieces of furniture than an electric piano, but there are reasons why people virtually give them away these days. If you do get one and then decide it's not getting used and taking up a lot of space, then they are a nightmare to shift on.