Question

Question is in the title really,
I want to know if I can check if the DB has been modified at all since the last backup, as my company change the data very sporadically and we end up with lots of backups all exactly the same.

Answer 1

You could query the last change to any index. This includes changes to tables, since tables are stored as a special form of index (clustered or heap):

select  max(last_user_update)
from    sys.dm_db_index_usage_stats ius
join    sys.databases db
on      ius.database_id = db.database_id
where   db.name = 'YourDbName'

These statistics are reset after a server restart. You can find the server restart time with:

select  create_date
from    sys.databases
where   database_id = 2 -- tempdb