A lot depends on whether you’re in the countryside or a built up area. In a town or village this shouldn’t prove contentious as you’re not creating a lot of new building. The converted garage shouldn’t overlook neighbours or block their light and the design should be sympathetic to the house. In the countryside, particularly if it’s in the greenbelt, things get a little more complex. Most councils impose limits on the amount by which a house can be extended and this could restrict your aspirations. However, it could be that much of what you want to do falls within so-called ‘permitted development’ tolerances. Talk to an architect or planning consultant to find out just how much of your scheme actually needs permission. Otherwise, garages don’t raise any particular issues other than, just occasionally, a query regarding contamination, especially if the garage has been used for home car repairs.