Sorry for the lack of reply. I am pretty new to MN and find it baffling that I don't get notifications of responses to my own threads!
We were thinking about buying a house that only has a 650 litre tank and it's pretty close to a boundary wall (25cm, current regs state 30 plus just for the footing surrounds).
I was trying to see if I could get an 1100 fitted in the same place but it would need some sort of fire resistance to be compliant.
But - we are not buying the house now - so that is that.
I look forward to the day I am no longer on oil, we have had it in two homes now.
Thanks for your replies.