Who has a gas/oil tank in their garden?

[PurpleCrazyHorse]

We're looking at houses a little off the beaten track and some of them have a gas/oil tank in the garden. We've never had one before, so what (oh wise MNers) do we need to know?

Is it really expensive?
Do you have to be in for the deliveries?
Are there different sized tanks, what's a good family size?

We don't want to disregard these houses but don't want to jump in without knowing a bit more about it.

Thanks so much everyone and some really good advice about checking the tank & filling it up in the summer. I'm not put off so will definitely consider a house with a tank (and will do my research if it's a gas one!). Good to know I don't have to sit in for a tanker if they can access it (explains why I've seen them near the front of properties rather than hidden at the bottom of the garden)

Thanks everyone :)