Make sure you use spring compressors before removing all four, its a lot easier as there will be no down pressure pushing on the joints, just the weight of the strut itself.
If you are sure of a date when you are going to do it, soak the alloy/ steel crimping joint on the bottom of the front strut to the main hub with "Plusgas" the day before and a second soak an hour before hand. It will come out very easily then, dont bother with WD40, plusgas knocks the hell out of WD40 when it comes to releasing siezed joints and bolts
For awkward nuts that never seem to budge no matter what you do
. I personally use a camping gas canister type blowtorch (homebase do a good one) assuming that there is no rubber boot or nylon nut thread to worry about, works a treat
One last tip:
Invest in a nut/bolt wind out type ball joint removal tool instead of the brute force chisel type, it will save you money in the long run by avoiding damaging the little rubber ball joint boots.
Also leave the nuts loose on all the ball joint threads until the ball joint has released properly. It prevents damage to the end of the threads, a nut can be replaced easily, a damaged thread is a true PITA to sort out if its damaged... Good luck