Not silly questions at all!
Not one of your questions I know, but in retrospect the best way to do your PPL is to do a good deal of it - at least to solo standard intensively in a foreign country where it's cheap. Book a holiday.
Doing it once a week or so here in the UK is expensive and often extremely frustrating due to weather and other cancellations.
Come back to the UK to do the last bit to get used to the conditions here.
Considering the total cost of your books is going to be less than that of one lesson in the air I wouldn't bother with ebay.
Also don't bank on 45 hours to get your PPL... 60 hours is about average.