You do not need a large garden to grow a massive range of interesting plants and flowers. The 2p coin gives some impression of scale to this Saxfraga cranbourne which is about the same size as the coin.

Note how it needs the protection of grit plus a sand and grit plunge bed as these small plants can easily be washed away and generally do not like damp roots.
Many alpines dislike wet foliage and would rot so I always water from below.

There are many species of Primula that could form the basis of an interesting miniature collection. This photo is of Primula allianii Joan Hughes. There is a National Auricula and Primula Society if you get keenly interested.

Similarly there are many Androsace to collect and experiment with. This display, in a 4 inch pot, requires several plants of Androsace carnea pyrenaica together to make the interesting shoe.
There is a specialist society within AGS for these small plants Androsace.org.
See a range of other pictures here .