Currently, Holding Down Bolts doesn’t fall into Construction Product Regulation (CPR) standards and they cannot be CE (UKCA) Marked.
Holding Down Bolts are manufactured per BS 7419](/standards/bs-7419-holding-bolts-basic-dimensions) (British Standard). This standard is not a harmonised standard like EN/ISO, which will allow them to be CE (UKCA) marked.
More about this can be read in BCSA memorandum No 17-14**.
In the new edition of EN 15048:2016 (after the standard will become harmonised), holding down bolts can be considered for CE (UKCA) marking after initial testing and suitability test following 5.2. d) of EN 15048-2:2016.
Currently, EN 15048:2007 edition is the only harmonised standard that can be used for CE (UKCA) marking.
You can also monitor a list of harmonised standards here.