Hello
Wait a couple of months and you'll have plenty. If you really want to
encourage it, hold down a few of the side shoots and cover them with
soil. You may need to peg them down with a few small twigs. The bits
that you buried will take root and the plant will spread. (It's
usually not needed).

If you haven't got enough to start with, ask your neighbours if they
have any until yours get established.

I've been using Swiss Mint for tea. It's a really refreshing coolmint
taste.
I grow it in a small bed (10ft x 3ft), where it can't spread too far.
It's about 3 ft diameter and 1 ft high. You'll have plenty in a few
months time. I think I use approx 10 leaves per cup, then add a
teaspoon of malt-extract. I've cut down on refined sugar.

A bit ot, but I like fennel-seed tea as well.

Cheers
AJ