I like it
Tamsin (as well as the variant
Thomasina and the similar sounding
Tasnim) lot, it sounds unconventional and very English. The full form is much better than nicknames such as
Tammy. Names I think have a similar "feel" are:
AnnikaAstraBrionyBryonyIndiaLyra
Other names beginning with t I like are
Theodora,
Theodosia and
Theophania.