Several of our clients have bought beach fronting homes and found the same problem. We have had success using a multi step approach. Firstly I would recommend a window film, a UV blocking one which helps with heat, glare and also helps protect your furnishings from fading. Try https://www.windowfilm.co.uk/buy-online/window-film-by-the-metre/uv-protection These films are virtually clear so it won't spoil your view or change the colour.

In conjunction with the film I would recommend voiles which which can be designed to suit your style, on such a large window it's probably easiest to have sheer curtains. But you can also explore electric sheer blinds which don't require any power such as those from Q Motion.

If none of this suits you then you can explore exterior electric sunblinds which you operate from inside. Good Luck!