They don't use antifoul, she's been berthed next to the visitor pontoon all that time, and serving beer. The vomit of sailing students has kept the growth at bay, following nights out designed to test their seasickness response the following day...
I'd ask the yard - you will only get answers from armchair gurus here.
Most paint companies, International, Jotun, Hempel have a premium product that can only be sold to professionals for commercial use - I don't think it contains TBT (and I'd have thought there would a hue and cry if it did - the Directors and owners of Sea Hawk went tp prison for 'recent' use of TBT). I suspect these premium pants are pretty toxic.
I managed to get a 20litre Jotun Seaforce 90 lasr year and applied 2 coats in late March, including raising the bootline 5 inches.
Really happy so far, not a scrap of weed or barnacle to be seen so far. The waterline has a browny green stain which looks better than the gelcoat covered in a fringe of weed. This antifoul is meant for 90 months use on ships and commercial craft.
Despite our motorsailer being a low speed vessel it appears to be working really well.
All Jotun products can be bought over the counter in Ireland and the Isle of Man, no 'certificates' or anything else required as essential in the UK.
Perhaps the fact that Jotuns "Leisure" products are very expensive has something to do with the difficulty of obtaining their well regarded commercial products.