Hi Gedmac
a warm welcome from me too
Your partner appears to have lost interest in the visual media (it may be that it requires too much concentration and may also be sensory overload for her) but still retains some interest in the spoken word ie LBC. I must admit I'm not a great music listener instead I love Radio 4 Extra as it has a variety of 'vintage' programmes and repeats of current ones eg the News Quiz, I wonder if your partner would enjoy this - and of course there's Radio 4
sorry if you know all about these - I do come across quite a few people who had no idea there was anything else but Radio2 (not that there's anything wrong in being a dedicated Radio 2 fan) and music does seem to help settle my dad (he loves his jazz and swing)
There are also talking books - have a look in your local library and ask what other services are available, and lots are available online too - and how about this for news to listen to
http://www.tnauk.org.uk/
Is she amenable to a bit of 'emotional blackmail' to get her out - and equally importantly for you to get out. I mean, how will she respond to 'I'd love to go to this coffee morning but I'm a bit shy of walking in on my own, would you mind being a dear and coming with me?' This way she feels no pressure on her and she's doing you a favour so she feels good? Same with day care - it's not for her, it's a favour to you so you know she's having a good lunch and a bit of company on a day when you need to ... (here make up or take up an activity - something to do with your astro physics maybe). I know my dad was happy to do something to help me out, but baulked if it was just for him - but he's been like this all my life, going with me to museums and such when no-one else was interested.
I do hope you've contacted your LA for an assessment of her needs AND for a Carer's Assessment for you - you may well be eligible for some support eg a sitter (maybe someone to read to her) and some respite. And do check with the council as if she is officially living alone and has a dementia diagnosis she may well qualify for a Council Tax reduction (dad didn't pay any at all).
do let us know how you go on
best wsihes