Cleanup/maintenance or overstepping my bounds?

So this is the situation I'm in. I brought my horse out to BC 2 months ago. I found a fantastic lady who keeps her own horses and a boarder already on her property of 10 acres. They all live outside with adequate shelter which was what I wanted for my mare. Plus, she offered me a working opportunity, so I don't even pay to keep my horse.
Now, the thing is, the place is a little rundown. Not to the point of being a safety hazard, but just a few things that need a fixer upper. What I would really love to do would be to fix up the tack room or shed/barn (or both). I have to get in there anyways and board up a hole where rats are getting into the tack room. I have offered to fix the fence before when my horse broke it, but she was adamant that her husband would do it. I know some people just like to do it themselves, their way (hey, I'm like that!).
Now, my dilemma is whether this would be overstepping my bounds as a boarder? I would like to do it as a Christmas gift to her and her family as she has been wonderful to me and I know they have limited time to spend on upkeep, but how should I approach it?

Simply put, do not do anything without first obtaining express permission to do so from the property owner.

Sorry, yes, should have been a little clearer. I will ask her before I do anything, but not sure how to approach it without it coming off rudely as "The place is kind of a dump, can I make it better?".
Not that it is a dump, but you know, that's how it may come off as.

Maybe just approach it as you told us...you like it here and since she seems busy you wanted to help without overstepping. Tell her you'd like it to be a Christmas present if you want but the way you explained it to us sounds fair.

I have boarders, sometimes it's hard to keep up with all the repairs/cleaning up with horses.....I would love if someone offered to do that for a Christmas present in appreciation of what I do daily for all the horses, just ask first and explain why you would like to help them out....

I strongly agree with discussing things 1st...many people can get used to having things done a certain way. Talking about it 1st lessens the possibility of stepping on toes unintentionally.