Hsb.
I don't know whether my garden is a cottage garden or not. I just plant wherever there is a bare spot. As a result, my garden is stuffed to the gill. Every square inch is planted many times over since I plant in layers.
As regards to mulching, I mulch whenever I can find the time and wherever I want to cover; for example, each spring I would mulch over spent spring bulbs such as Scilla, snowdrops, mini narcissi and baby plants and allow only some of baby plants to grow.
The last time I bought mulch was probably 30 years ago. I have been getting mulch that I can get for free, e.g. shredded leaves, woodchips, horse manure mixed with bedding, straws/haybale, etc.
You will have to try and learn and decide what works best for you, because what works for others may not work for you. Gardening is a lifelong learning experience. Enjoy!