When it comes to bigger things like houses almost everything can be done competently by DIY but you may have to do a bit or even a lot of study on the specific topic for some jobs. Start with smaller simpler jobs to gain experience and work up to the more complex. It can be very rewarding. It can save a fortune, but can take time. Here we need to disclose a vested interest, doing repairs often needs tools.
If you know something about the work and don’t want to or don’t have the time to actually do a job it will at least help in talking to a builder about what is wanted. You are paying a good builder for knowledge, skill and time which may be well worth it.
Early in my start at DIY I needed some gas pipes changed. A British Gas engineer did the job, turn the gas back on, left and I discovered a cut off gas pipe unstopped pouring out gas. I decided that I needed to learn about gas work and did my own for years after. Now the government and trade bodies insist on training, certificates and registration for work on gas systems. Many other trades need certificates for commercial work, it keeps the training bodies well funded, but often you can do the work for yourself even if it needs mandatory checking after.
The competent builder often isn’t allowed to do work without certificates so they and you are also paying for this.