Though the 118 puts us in the 'worth a go' category, will the 108 blow us out of the water?
No, but the panel will have to take a view - based on the evidence - of which score is a better indication of ability.
Does being out of area make any difference? Can we mention lack of in-school preparation, for example?
Yes, although it probably won't carry huge weight, otherwise everyone out of county will be seeking positive discrimination! In any case, the official view is that the familiarisation + practice tests are sufficient.
Does the fact we're only applying for what (from most reports) will be an under-subscribed school make any difference?
No, particular schools are not considered at this stage.