Yep, MAN777, you are indeed right.
Likewise, you'll notice that the £5 online check-in fee never applies to 'sale' fares (i.e. whichever are included in the current promotion). Ryanair never advertises any fare other than the current promotion, so if you choose a flight that's not included in the current promotion, you'll get stung for another £5 per person per sector.
This is slightly more subtle, because the law seems to state you can't advertise a fare that accrues an additional fee. FR avoid the debit/credit card fee by always exempting one type of card. They get round the online check-in fee by simply never advertising those fares that have it added.