We've recently moved into a new house, and wish to make a few minor
alterations in the (smallish) garden, specifically to grass over part
of a flower bed surrounding the patio (our kids seem not to have the
ability to step over the bed to get to the lawn) and to remove a
dangerously leaning tree in the middle of the lawn. The latter we
have already done but it has left a crater in the lawn to fill; the
former will require raising/levelling of the soil to match the
surrounding lawn.

With the house we also inherited a reasonably-sized composter, full of
compost. I haven't seen what it's like, but this leads to my
question, which is:

Can you use compost (of the variable homemade variety) as a base for
lawns? I'd rather put the compost to use (we don't have a huge plot
to make a great deal of use with it, and a second composter is already
filling up), and avoid the cost of buying in loads of topsoil. On the
other hand, I gather that topsoil, from the right supplier (i.e. not
B&Q etc) is not overly expensive, so I would rather use that (or a
mixture of topsoil/compost?) if it will provide a better result.

Many thanks in advance,

Mike