Crosslink from Ebay, and try ASDA for lenses, make sure you speak to the proper optician, especially if you need varifocals or anything complex.
I got some of their own frames with photochromic varifocals , thin lenses for £80, very happy, wished I’d put them in some crosslinks.
They will glaze frames you take in for £40. I’m -7.0
It sounds unlikely, but I’m very happy.