Everyone will be in the same boat, however, you can help her with just simple things for year 4 children. Reading and comprehension, so asking lots of questions about the story, why does someone feel that way, why did John do that do you think, what do you thing will happen next? Write an alternative ending. Look at the language used to describe how someone feels or how they look.
For maths, telling time on an analogue clock, then a digital clock and understanding the different ways we say time, such as ten past and ten to. Converting am/pm on a digital clock to a 24 hour clock, understanding that we add 12 once we get into the afternoon because 12 hours has already past.
Times tables and the inverse, so 5x6 = 30 but also 30 divided by either 5 or 6. Learning all the way up to 12x12 will be incredibly beneficial. Play with coins, tip out a pile and push coins towards her and get her to have a running tally, if she struggles, have a pencil and paper handy to help. Doubling numbers, looking at place value, bus stop division.
This is just off the top of my head (I volunteer in year 4) but you can ensure that she can progress her education whilst she is at home. Swimming lessons are great but the practising is what really helps. I always liken it to a musical instrument, having 1 lesson a week is fine but you need to practise inbetween lessons.