I would make sure they actually have the load rating. Previously these were only rated at 735kg although there were discussions of having them retested.
Could be my next set of wheels if the rating is there.
Just make sure you check the wheels are truly rated at 880kg. There should be a stamp or similar on the back of the wheel.
As you have a t32 the correct wheel loading check will be part of your mot amongst other considerations
I ran 8.5" ET45 and they did need to come out towards the arch slightly, but by slightly I mean another 15mm or so, to make them sit level with the arch. So your fronts will be about perfect as an ET35
A 10.5" ET35 will have over 35mm poke than my old set-up. These might either poke out too far, or catch the arch, depending on how low you are.
I know people run 10.5" rears, and i've even seen people run 10" fronts with a pretty extreme offset, but 10" rears are my maximum choice, and that's what I run now.
A lot of what you are doing will depend on your suspension drop, if you have one.
Are your 10s 20" rims? Cause at the moment I'm running 9.5 on the front thinner tyres cause every time I turned kept on rubbing the inner wheel arch. Plus hard to get load rated tyres on 40s.