I second the posters who have said sign her up to Brownies/Beavers. She will get to try so many new things and it is very reasonably priced (I pay £12/month for beavers, South east).
As for other opportunities@hunnsh , you just have to do your best with what you have available. There are loads of cheap workbooks in poundland, the works, home bargains etc. Some are less than £1. Get some and work through them with her, or ask her to do a page or two while you are cooking/in the shower/before she watches tv.
The internet is a wonderful resource. I bought my son a second hand guitar for £10 and we are watching lessons on YouTube. Could you do something like that?
Similarly, there are loads of songs/lessons on maths or science or English or foreign languages or history etc on youtube too. Watch them together, build it into your weekly routine.
Explore non-classroom things with her too, like cookery, gardening, drawing, clay modelling, sewing, cycling, whatever it is that interests her.
Look at your local library, they may run computer coding clubs or lego building clubs or book clubs for her age group, often reasonably priced/nominal donation/free.
You are right that it isn't fair, but you are being unreasonable if you let that be the end of it and don't try to offer her as many opportunities as you can at home.