Všechny názvy tabulek získáte z INFORMATION_SCHEMA.TABLES. Stačí tedy použít svá kritéria a získat je:
select table_name
from information_schema.tables
where table_type = 'BASE TABLE'
and table_name like 'xx\_______\_T' escape '\'
and table_name >= 'xx_' + CAST(@FirstTableMonth as varchar) + '_T';
SQL housle:http://www.sqlfiddle.com/#!6/7b4f5/ 2