What's your business name? If it's got 'Tanning & Nails' in the actual name - like at the bottom Cupcake Tanning & nailss, then if you go into tanning classification, you will get tanning clients, who may talk to you about nails during their appointment. If you go into Nail Techs you'll get nail enquiries & they may ask about tanning etc.
I worked for YP and sold advertising in the Peterborough, Leicestershire & Northampton books, but they are all the same.
If you want to have your hair cut - you'd look at hairdressers, if you looking to buy a bike, the cycle retailers.
If you want a spray tan - Tanning. It does also direct you to Beauty Salons in my book.
I know it's hard, especially when money is tight, but think about where your competitors are??? They must be getting results from it, so go with them.
Again, as I said in the above post, look at what enquiries you want. Do you want more nails or tanning? Which is more profitable, etc. Choose accordingly.
If all else fails, go for the £100 + vat and put it in both. You can pay by 10 installments interest free.