Best place for Tuberaria is actually at Porth Diana, Trearddur where they are always bigger. It is on the cliffs between south and north stack. Look for pole and metal rings then look inland towards the lake. Faint path from lake to cliffs points to Tuberaria.
Relatvely new addition to the British flora Equeisetum x meridionale is near Anglesey Airport by Llyn Penryhn. Car park at the end of the lake.
On the other side of Anglesey at Lligwy is Equisetum x robertsii and Equesiteum x font-queri.
Don't forget you are a short drive from Cwm Idwal too where Awlwort and Sax cespitosa will be out.