Granny flat/annex

[Theknitwitch]

Need to find property where we can either convert existing lower ground rooms, or add to property to create a 'granny flat' for MIL. Has anyone done this before, and do you have any tips for how best to go about it.
Any advice greatly appreciated.
Thanks

Building something from scratch is expensive. What about converting a double garage?

Theres a granny flat company that builds flat pack units for about £30,000 always advertising in the back of the Sunday papers

Thanks for the responses. If we can find property with double garage we'll go with that, but flat pack might be an option if we can do it for about that price.