@cassolotl I have splints from ringsplintsbyzomile.co.uk and one fancy thumb splint by We Design silver splints (but I needed a hand therapist prescription for that).
Before I had the silver splints, I used oval-8 plastic splints. Some NHS hand therapists will prescribe these and some won't (sigh). I used to buy them from http://www.3pointproducts.eu/ (cheaper than buying them singly).
Basically, I tried the plastic ones first, then upgraded.