they send you a reminder mate then you can go online and pay, you can make an account on the basc website and it manages your stuff like changing address etc
I think the options are full, bi-annualy or quaterly .. maybe some different options but you can definitely split the payments down
I've always renewed but from what i've seen on the paperwork i think it just expires.. like i say mate i always renew so im not 100% on that